# What would cause full body armor to return?

Many times in sci fi, the concept of full body armor has come up again and again. Most famously in Star Wars where we see Stormtroopers wear white armor covering their entire body.

What I'm wondering is why? Modern soldiers wear armor that only protects a small region of the upper torso and head to save on weight and have better mobility.

Why would a future military have standard issue armor that covers the entirety of the body?

Some assumptions:

• The material the armor is made of is light and strong enough that it does not burden the solider much, or at most requires assistance in either a passive/very minor assistive exoskeleton to operate with.
• Guns and projectile weapons over all are still a thing.
• Covers at least 75% of the body if not fully. Nothing is stopping use from going the way of the peasant soldier i.e. focusing on head, torso, arms and hands protection. Maybe leg armor too, if you're lucky.
• The soldiers wearing this armor are in a terrestrial environment.

• So why would a future military have standard issue armor that covers the entirety of the body, especially when it literally never does any good? Jan 2 at 19:44
• Presumably, stormtroopers armor can also serve as a vacuum suit. Jan 2 at 20:54
• "So why would a future military have standard issue armor that covers the entirety of the body?" In some sense we have that today - we just call it a tank (or APC, etc). Jan 3 at 0:25
• @RBarryYoung Not a vacsuit per in-universe explanations, but more akin to CBRN gear you might find a modern military using (plus of course the ideological aspect of making the force even more outwardly homogenous). Jan 3 at 1:55
• There's an often overlooked nuance to body armor that civilians frequently miss - it's not intended to make the user immune to attack, but to increase their survivability and staying power. Grazing shots and glancing blows that don't bleed mean your effective fighting force retains it's numbers longer with fewer losses to shrapnel, infection, etc. Armor won't make you immune to an IED, but it CAN effectively reduce that device's kill radius. Jan 3 at 18:22

## 18 Answers

Environmental dangers

Space is a dangerous place. You may find that you're more at risk of dying from radiation or lack of oxygen or heat than by being shot by the enemy. Sure you might get instantly obliterated if one of their ship artillery hits wherever you are on the ship but should you survive you want to be protected from dangers such as depressurization and lack of on-ship life support systems.

You will need to be protected from head-to-toe in order to be protected from most if not all environmental dangers, especially in space, which is what I'm assuming is the general environment of your setting by your use of storm troopers as example.

• To some extent, if you knew your crew were all suited and self-sufficient, you would depressurise those areas prior to battle, to prevent enemy artillery from causing catastrophic decompressions or risking fires in those areas.
– Nij
Jan 3 at 6:46
• @Nij they do that routinely in the Honor Harrington stories.
– ths
Jan 3 at 16:44
• Modern EVA suits on the ISS are designed to be literally bulletproof to protect from tiny, high-velocity bits of debris. The issue with duplicating these suits for a military application would be cost, as an EVA suit costs about $12 million. Jan 3 at 18:49 • @MarkPrice the main reason "an EVA suit costs about$12 million" is that they're made bespoke, and by hand, not mass produced. Any endeavor which needed to outfit an entire military with something similar would quickly benefit from economies of scale. Jan 3 at 20:57
• @TheoBrinkman This is space. Everything will be astronomically expensive without some radical technological overhaul. Jan 5 at 1:42

Body armor is designed to protect mostly against the type of bullets we use.

These bullets produce localized damage. They don't fly that fast. Some body parts are more vital than others. Armor is heavy and cumbersome. The enemy will aim for the center of the chest because it's a lot easier to hit than the head. So it makes sense to only put armor on the most vulnerable parts.

To justify full body armor, you'd have to change one of these parameters.

Remove the current rules of engagement and allow for poisoned bullets that kill you even if they hit you in the pinky finger... or white phosphorous, or explosive bullets... then damage is no longer localized, and most body parts become vital. In that case, you would need full body armor.

Change the enemies, for example give them acid for blood that sprays everywhere when shot.

Make flamethrowers legal! Everyone get an asbestos suit!

Fight in vacuum: any hole in the suit means a very bad day, so it has to be bulletproof everywhere.

Make aiming more accurate, for example robotic auto-aiming space pew-pew lasers that travel at the speed of light, or homing bullets that can reliably hit any non-armored part on a moving target. Then you need to armor everything.

Use the Space Shotgun instead of the space rifle. I mean, if you're shooting people inside a sci-fi spaceship you probably don't want to use .50 cal or armor piercing bullets that will go all the way through the ship and puncture the reactor confinement or just blow the air out. So you'd use space buckshot instead, which works better in close quarters anyway. If the enemy uses space shotguns that aren't armor piercing, you don't want a heavy thick chest plate because the spread of the shot means you'll get hit somewhere that isn't covered anyway. It would be better to have lighter protection and more coverage.

• Look up frangible bullets for inside space craft. Feel free to add that if you want. en.wikipedia.org/wiki/Frangible_bullet Jan 2 at 21:28
• Frangible space buckshot! Jan 2 at 21:51

There exist already today full body armors: hazmat suits

In a scenario where the enemy can use biological, chemical or nuclear weapons, you want to avoid that those substances enter in contact with the body of the soldiers. The only solution is therefore to fully cover the body and leave 0 exposed surface.

• True, but it's not exactly armour. Per the question, that would explain the black under-suit, but not the white armour shell on arms and legs. Jan 4 at 11:36
• @Graham hazmat suits in that picture might be fine for post-combat cleanup, but are ill-suited for combat itself, where necessity of fast motion, sharp edges, enemy projectiles / laser beams etc. would quite easily make a holes in them or rip them, making them quite useless. So you would need white armor protecting that sealed under-suit. Jan 4 at 21:36

# One New Thing (Name Your Problem):

All you need to justify head-to-toe armor is ONE new attack form that requires armor to protect from it. It doesn't matter WHAT that is, as long as the logical defense is armor. It doesn't even have to be an attack currently in use - even knowing the enemy WILL use it if you don't defend against it will require everyone to be armored. And a suit isn't enough, because the slightest breach of the suit will kill you.

• SONIC WEAPONS: Sound weapons are developed so lethal or debilitating sound waves cripple the nervous system. Only adding vibration-cancelling protection to all parts of the body keeps out the sonic attack. If armor can be made to absorb shockwaves, this can even apply to reducing ubiquitous blast effects.
• NBC: Nuclear, biological, and chemical weapons mean chemicals, radiation and disease are able to penetrate to a man not covered everywhere. Chemicals can include things as humble as irritants. Only constant isolation protects you. Anthrax can be everywhere and new strains made to overcome the best immunity.
• INCOMPATIBLE ENVIRONMENTS: Alien worlds, ice-cold arctic winters, deep ocean, hydrochloric acid atmospheres, space, the list goes on and on.
• KILLER MICRODRONES: Tiny robots are everywhere, and out for human flesh. The armor needs to be strong everywhere to keep these evil things from finding a vulnerable spot. And perhaps you need to periodically douse in acid or flaming gasoline to kill off the things as they accumulate on your gear.

That list could go on all day. But in addition, there are other reasons to completely protect your troops.

• YOUR COST PER MAN IS INSANELY HIGH ALREADY: Each trooper requires vastly costly training and equipping to make him effective, or the men who can fight are wildly rare. Maybe 1 in 100 men is immune to mind control, or 1 in 1000 is psychic. Maybe you need a PhD to operate the linear accelerator cannons in all the possible situations. Or the effort to deliver one soldier to the battlefield costs a billion dollars (teleporters, interstellar travel). No cost compared to that is too high to assure each man is able to fight to peak efficiency.
• EVERYBODY USES POWERED EXOSUITS ANYWAY: Every man needs to operate completely independent of the supply chain or the equipment (weapons, life support) they use is too heavy to move in without an exo-suit. If you can haul 10 tons of gear, what's half a ton of ablative projectile & heat resistant plating amongst friends?
• PROJECTILE-RESISTANT OPPONENTS: If the enemy (zombies, super-armored guys, shock-resistant aliens, robots) is resistant to small penetrating projectiles and the tissue shock that goes with it, they might close to melee range without being substantially slowed. Against that alien's fire breath, acid spit, claws and swords you're going to want to have a full-body suit of armor just like the ancient knights did as you incinerate the still-moving chunks of your opponent.
• INDEFINITE SURVIVAL: Your battlefield can't guarantee your soldier supplies. Your suit recycles CO2 into sugars, amino acids and oxygen. It's your food, clothing and shelter. Every bit of you is covered because every bit of anything that comes out of you is recovered. It's like a Fremen stilsuit and space suit hazmat suit and body armor all in one.
• SHRAPNEL: If your battlefield is full of high-explosive weapons blowing everything everywhere to tiny flying bits of shrapnel, the primary threat becomes either vaporizing (not much you can do about that) or getting hit with tiny projectiles that can cripple your soldiers. Without head-to-toe armor, no soldier will last more than a few minutes before they have so many minor wounds that they can no longer function. VR goggles tied to sensors let you see through the smoke, VR hearing means you aren't deafened by the blasts, respirators mean you can breathe when the air is full burning gasses. You can walk through the burning buildings, absorb some of the shockwaves from explosions, and so on.
• MEDICAL: Your suit is a walking medic. It detects injury anywhere on the body instantly, administering stabilizing chemicals and immobilizing crippled limbs. It tourniquets at the sight of bleeding, inactivates pain locally to allow a soldier to withdraw or keep fighting.
• ZOMBIE SOLDIERS: In the event your soldier dies or is crippled, the suit can activate the exo-suit and continue to operate. It will move the soldier to a medical facility or fire on opponents without the appropriate transponders. Dead soldiers can be 'ordered' into suicide attacks to draw enemy fire or carry bombs to destroy enemy positions. How terrifying is that?
• YOUR ARMY CONSISTS OF WEALTHY FOOLS: If your army is a group of poorly trained volunteers but supported by a nation of great wealth, then the sons and daughters of the elite are walking into a gunfight without the skills they need to live. Maybe your advanced society has forgotten how to fight wars as wars disappeared. Maybe it's a bushido thing where the elites lord it over the commoners but have an expectation that they be willing to fight and die for the nation. The solution? Those ridiculously expensive suits of armor that protect the fools from the consequences of their own actions. Once they figure out how to fight again, they're used to the \$2.5 million dollar gear and don't know how to fight without it.
• 10/10 list. Also you can easily combine almost all of them with each other so there are multiple reasons. Jan 5 at 13:42

Homogeneity.

Who are the officers? Who is telling people what to do? Who are the high value targets?

If soldiers have their entire bodies concealed it is harder for an enemy to figure out which soldiers warrant more attention. Additionally, if you are a soldier, uniforms of this sort will conceal the fact that some of your fellow soldiers are aliens, or robots, or resurrected zomby soldiers.

• This could work well especially if the suits also contain some visor thingy that allows you to discern between your own soldiers and commanders - to the enemies everyone's the same, to you everything's clear Jan 3 at 9:53
• this will of course cause the same level of confusion among your own soldiers, who's orders should I be listening too, who do I look to for orders, who is specialized in X, who has clearance for this, Who is actually a soldier and not an imposter, who is slacking off or gone missing, oops followed the wrong squad again...
– John
Jan 3 at 16:30
• Why do you need full body covering for this though? Simply dress everyone in the same fatigues (as modern armies do), and ban lower ranks from saluting on the battlefield. Jan 4 at 11:37

## You've already answered your question

The material the armor is made of is light and strong enough that it does not burden the solider much, or at most requires assistance in either a passive/very minor assistive exoskeleton to operate with

If the material is so light and unencumbering, then there would be little need to leave out armour pieces for weight or mobility. And so, given that an armoured bodypart is more resilient than an unarmoured part, it would be a no-brainer to cover up the entire body

• This does give you the question: why would you not use the saved weight to add MORE protection to the torso and head instead of adding protection on other bodyparts as well? After all if you can choose to either double the protection on your chest and head or add protection to the rest of your body... what would be a better choice? Losing a hand or leg might not seem fun but if it increases the odds of both surviving and being able to continue fighting after a hit there is a good argument not to go for full body protection. Jan 2 at 9:42
• @Demigan Modern body armor that only covers the head and torso is just as heavy as a full plate armor was in the medieval period. Knights were not just protected against kill shots, like modern soldiers, they were protected from nearly every manner of debilitating attack. A modern solider is still quite easy to disable if your spray them with a few bullets, but full body armor that can stop nearly all small arms no matter where hit could not just keep you alive after being sprayed by bullets, but keep you from being injured or removed from the fight. Jan 2 at 23:16
• @Nosajimiki well thats the point: FIRST you would add enough armor to the torso and head that you'll survive just about anything and THEN you might consider adding armor to other places. The alternative is "if we add more armor it becomes so thick it limits mobility so we add the extra armor on the rest of the body". Jan 3 at 5:15

Armor must be effective against the primary threat.

Platemail went away because it as guns become sufficiently advanced, they cease to offer sufficient benefit frequent enough for its cost and burden. That doesn't mean armor went away entirely, they just might not be in the form depicted in Star Wars. Kevlar vests, ballistic armor, etc. do exist and are frequently worn.

1) Material science advance sufficiently that body armor can sufficiently protect against the most common threat.

There can be multiple methods armor mitigates damage, and depending on your world the most common source of damage need not be kinetic in nature.

• Direct (As conventionally known)
• Ablative (Reduces or Eliminates the material from the incoming attack)
• Absorptive (The armor takes away the incoming attack from the weaerer, perhaps absorbing an electrical charge, or perhaps taking all the impact force in the wearer's stead)
• Dispersive (Maybe in your world bullets became obsolete and energy weapons became dominent, the armor disperses the energy harmlessly across its surface)
• Insular (Is the primary source of damage through biological/chemical warefare, or even electrical or heat?)

2) The environment or operational conditions warrants it.

Maybe your characters live on a hazardous planet. Maybe rockslides are common, toxic gas, heat waves, etc. Maybe they live under the sea. Armor isn't limited to combat use. Real-life Exoskeltons will probably see heavy duty use in the form of mining etc. before combat use, that doens't mean your soldiers cannot equip such an armor for non-combat purposes while on active duty. Once it is established that operational conditions warrants such an exosuit, they might start adapting it for combat utility based on field experience, but such a suit's priamry function will be to fulfill operation conditions.

## Psychology + Uniform

Even light plastic armor with some kevlar under it goes a way to protect from discontent civilians. At least if the solders are in compact group. Also it improves their morale, as they see brave friendly solders around, even if they are scared inside. It protects from inconvenient scratches, or in case of falling from speeding motorcycle. Even if soldier is wounded, enemy cannot say how much or even wheter - so until really disabled every unit looks like fully functional.

Full body armor looks intimidating, may have demon-like face and does not show, if it contains scared newbie or hardened special unit veteran (but suggest the later). As such units are usually used against civilian "rebels" in big number, this looks make half their work done - week civilians take cover, run away scene and only "hardened criminals" are left to oppose such power demonstration.

Also having the same armor makes good uniform, to recognize your man from opposition fast. And small and cryptic distinctions make easy to be spotted by trained eye and recognize to fast evaluation of who is from which unit, which specialisation or which level of authority.

Plus it is easy to mass-produce such armors and have soon big army where only few are really trained, while it looks, like all are top specialist. Good for evel overlords as well for film studia :)

• of course scary masks also makes it harder to deal with non-combatants, which is a bigger and bigger part of a soldiers job and full body armor concealing injuries also makes it harder to assess and more importantly treat injuries,
– John
Jan 3 at 16:34
• As evil overlords I rule by fear, not love :) Anyway today police use similar tactic against demonstrations (just black variant, body armor and the rest hidden, also anti-riot shields - not pink uniforms with unicorns/Hello Kitty). In near future I suppose at least simple monitors to state, if and what inner part of armor was damaged - so what is possible injury. If it is light exo-skeleton plastic type, it can be designed to strip as fast as classic uniform, if not faster. (Compare downhill skying-shoes - no knots and laces prone to ice, but just flip few clips and the feet is free). Jan 4 at 1:36
• For less evil overlords / friendly rulers (or goverments) it is still good as anti-riot, fast overtaking units and power demonsrtation, which is to take the land/place and establish basic war ruling. Second wave will be in contrast much more human looking powers (say like normal police+byrocrates) set to establish civilian rules, all evidence, healthcare, taxes, hospitals etc.. and vissible improvement from that scary first wave - old good sugar+whip tactic. (And third wave civilian looking undercover agents / inteligecy members ) Jan 4 at 1:47

## Laser weapons

Their armour looks shiny..

Modern armour material can be reflective, that is why it may return.

In Star Wars, the stormtroopers have a light weight, reflective white armour.

Edit: In real life, strong laser beams will damage mirrors, same would happen to armor. A shiny armor would be most effective compared to clothes, when the angle of the laser light is not perpendicular to the surface. In any case, the comments below are justified.. body armor against laser should be thick and (very) heat resistant as well !

• Not really. Any weaponized laser would burn the surface of even the most reflective mirrors we can currently conceive. While a fraction of the laser will be refracted and has a high chance of blinding anyone seeing the scatter the amount of the beam that is absorbed by the reflective surface will burn it and reduce its reflectivity for the rest of the beam, which burns it more until its as reflective as non-mirrors. Unless your mirror is in excess of 99.999% reflectivity or the laser is outperformed by normal bullets its not going to be useful. Jan 2 at 18:18
• That said, armor can be very effective thermal insulator; so, even if it does not reflect the laser, it can block the heat of the laser to prevent harm. Jan 2 at 23:20
• Laser on the battlefield will not always hit perpendicular. I think reflectivity would at least help reduce the energy to be absorbed by the armor. Clothing would not protect at any angle. Thanks both for the input, I've put an edit. Jan 2 at 23:37
• @LotenPechtel explain that one to me? That doesnt seem to solve the problem as the retroreflectors would still burn and absorb most of the beam anyway just like a mirrored surface would. Because that is the problem: the first part of the beam would hit, and the part of the beam that is absorbed burns the surface/retroreflector causing it to absorb more of the rest of the beams causing it to absorb more and by the time the beam ends (which likely takes a fraction of a fraction of a second) the surface/retroreflector has absorbed most of the beam's heat, which is the point of a laser weapon. Jan 3 at 5:22
• I'm not an expert on the subject (despite the answer) but it seems laser mirrors come with a damage threshold actonoptics.com/products/ndyag-mirrors Jan 4 at 7:25

## Armor Simply Needs to Become Lighter

Full body armor is always better than partial armor as long as it can meet the following two criteria:

• It must stop all common threats when hit.
• It must not be so cumbersome as to make one combat ineffective.

If you make your armor too thin trying to get full body coverage, it will not stop any common attacks; so, it is just waisted weight, but if you make it too thick or too heavy, then you can not move in it which also makes it useless.

The only reason we do not still use full body armor is that modern armor is not good enough to cover the whole body and stop a common riffle round without also being too heavy. To fully cover a solider today with riffle armor would mean loading him down with over 100kg of body armor; so, to compromise, we use armor that weighs just as much as a suit of medieval plate armor did, but we focus that armor only on the most critical and likely places to be shot. If you were to improve armor enough that you could stop most common riffle rounds with a full suit of armor that still weighs 25kg or less, then full body armor would very quickly come back into common usage.

Alternatively, if you were to improve a soldier's carry capacity to over 100kg using cybernetic or biological augmentation, then you might also see an increase in full body armor, but... this may be less likely since a higher carry capacity also means you can carry a bigger gun; so, higher caliber weapons may also become the norm simultaneously eliminating the advantages of more armor. So if you were to try to solve this problem with super strength instead of lighter armor, you need to make sure that the main threat will still be normal soldiers packing things in the 5.56-7.62mm range. So super solders have to be the exception, not the rule, for this solution to work.

Lastly, the problem we see a lot in sci-fi (and a lot of fantasy actually) is that common attacks go right through full body armor. When you look at something like a storm trooper, full body armor makes no since because every common hand gun seems able to go right through the armor and kill them, even when hit in the chest which should be the most armored part. However, if you instead envision something like the Kull from Stargate, you then have something that makes a lot of since to see full body armor on. Since their armor is actually effective at stopping most common weapons, they can walk right out into a hail of bullets taking shots to the arms, the legs, the face, the chest, and everywhere else. This means they can focus their whole effort on shooting the enemy and not have to waste any effort on not getting shot.

• Agreed, the only reason we don't make full body armor today is full body bullet resistant armor would weigh hundreds of pounds.
– John
Jan 3 at 4:05
• @John And because modern militaries have other units that can fill the role of armored cavalry. They just aren't knights anymore.
– Ray
Jan 3 at 16:37
• @Ray what dos heavy Calvary have to do with it, every soldier would wear full body armor if it was light and effective. Also in the past infantry also wore full body armor.
– John
Jan 3 at 16:51
• @John I think what's he's saying is that if tanks or vehicles did not exist, you would inevitably end up with a small number of specialized, very heavily armoured troops to fill the role even if body armour was otherwise too heavy for regular troops. Jan 4 at 1:48

Secret police or collaborators from an occupied country.

Occupying another country is hard. Doing it with just my troops from home? Now that's tough. So I need some locals to help out, but the local population isn't on-board yet with my leadership and I don't want my people hassled when they're off the clock.

What better way to protect them than to conceal who they are with full body armour and face coverings?

I'd say that the previous answers have covered most of the reasons why armor could return.

Effectiveness against commonly-used weapons

To add to the above, if the materials from which armor is made prove to be sufficiently effective against "short range" weapons (i.e., machine guns, pistols, shotguns, grenades) they would normally encounter during combat, then you'd have an argument for them to make a return.

Intuitively, as no sufficiently-light AND comfortable armor can protect from a hit to the face or hands, there is no reason to inconvenience soldiers with it, but if technology allowed for a face cover or "armor glove" that would save you from it, and be comfortable enough as stated in other answers, then military forces would definitely incorporate it.

Effectiveness against new weapon types

If the materials, alloys or fibres from which armor are made are better suited to stop or deflect new types of weapons (i.e., beam weapons), such as Star Wars' armor, which is supposedly "designed to disperse the energy of a blaster bolt and insulate the wearer, lessening injury", then full body armor would make sense.

This ties to the previous: if, for example, beam technology became cheaper, safer, more economically efficient or better overall, then militaries will switch to beam weapons and full body armor might be the most reasonable counter.

The armor incorporates a powered exoskeleton. It allows the soldier to carry the armor, and its power supply, without increasing their burden.

It will also allow the soldier to carry additional ammunition and supplies and even heavier weaponry. It could also include environmental protections (possibly including heating or cooling) that would not be practical for a soldier without such a suit to carry.

• Started my answer quite a while ago, but didn't get back to the page until now to press Submit. An hour after @ThisIsMe submitted his answer. Jan 3 at 16:58

It's already returning. E.g. this is the Sotnik infantry armor that Russia is developing, planned to be done 2025(picked it as an example, because it looks the most sci-fi ish, there are plenty of others): https://taskandpurpose.com/military-tech/russia-sotnik-combat-armor-development/

You must remember, that body armor didn't go away due to ineffectiveness as such, e.g. 17th century plate was quite effective at stopping muskets from all but point blank range and would have been for a couple centuries more, until muskets went away, the word bullet-proof comes from the literal proof that it would stop a bullet that the purchaser required the armorer to provide in front of him:

However, due to the large quantities of high quality, tempered steel required to do it, it was too expensive to mass-equip the new armies of the modern age and due to the fact that no armor would do squat against cannon anyways, the cost-benefit equation worked out to: heaps of cheap unarmored troops > a small number of armored troops.

The tech for at least somewhat effective 3/4 armor has arguably existed since the 80s, but it was too expensive for the mass armies of the time.

Now, all militaries, including the Russian one are moving in the direction of a relatively small number of well-trained(hence valuable) troops, so the cost-benefit equation has shifted back to armor.

• Or alternatively, the cost of manufacture goes down due automation or some other new advancement. Jan 3 at 20:31

As you stated: the main reason that soldiers today only wear light partial armor is due to weight. The encumbrance of full-body armor outweighs the benefit of full protection.

To get back into full armor, one or both of that must change: either full body protection must become a definite benefit, or the weight of the suit must be reduced (or both).

One way to do this is with some variation of power armor. Things like exoskeletons that do exactly that are already in development. Such a suit will at least support its own weight, making encumbrance a net-0, and if it increases carrying capacity or walking speed, it gets to be a complete benefit.

This can be combined with benefits that other posters mentioned; like protection from environmental hazards (poison, or the vacuum of space)

## The balance of Offence vs Defence swings the other way

Right now, the problem is that an armor that can stop a bullet in its tracks is expensive, heavy, inflexible and generally only good for one or two hits with low-calibre weapons.

Weapons technology has vastly outstripped personal body-armor to the point where we no longer defend against direct attack. Instead, we defend against secondary effects. Shrapnel, debris, glancing hits. Things that would cripple but usually not instantly kill.

This, incidentally is the ideal-case for a Storm-trooper's plasteel armor-plate.

Remember the prison-block in A New Hope? Remember how fast the fire-fight turned it into a storm of debris, shrapnel, smoke and alarms?

Those storm-troopers might die in a single direct-hit, but they shrugged off the shrapnel caused by blaster-fire hitting walls and blowing up nearby hardware like it was nothing. And they started shooting before the smoke from breaching the doors had cleared. Those helmets have all kinds of respirators, filters and optics to let them fight in hostile environments where a lesser-equipped person would be blind, choking and probably dead.

We also never see a clear over-penetration of the stormtrooper armor. Plenty of burn-marks and troopers falling over, but plenty of times a trooper was clearly still alive after being hit. For example one trooper fell off a catwalk when directly-hit and was clearly screaming as he fell.

One imagines that the storm-trooper armor is actually excellent as a defense against lighter blasters (such as their own E-11 carbines and hand-blasters) and most of the storm-troopers we see shot are actually alive, just knocked on their asses by the impact and burns they just received.

So back to the offence/defence tradeoff.

Stormtrooper armor is very light-weight. The clue is in the name "Plasteel", a lightweight polymer with properties reminiscent of steel.
If it weighs anything like say.. ABS, or a thermally resistant resin, it could be very lightweight indeed.
An armor that defends against most non-military small-arms well enough to prevent the trooper being killed in many/most cases, and can turn a military-grade glancing hit into something survivable, provides NBC protection, can see through smoke and gases, shrugs off shrapnel and acts as highly functional riot-gear?

Sounds great.

Now imagine what that would look like in real-world modern terms.

A suit of body-armor that can stop pistol-caliber hits entirely (even if the wearer gets knocked off their feet), and can turn a killing blow from larger caliber weapons up to .50 cal into something survivable.

We don't have the technology for that right now, but if we did, we might see the return of the suit of full body armor.

Your military strategy emphasizes sheer numbers and brute force over everything else. Remember that the Stormtrooper example is based on what is essentially a limitless clone army. Not all of them will require this level of full-body protection, but some will, and the full body armor is standard issue to all. It's the mass production of troops, without any exceptions or differences whatsoever, right down to every element of gear. Each branch of the U.S. military has its own standard working uniform, and each MOS has a relatively standard issue of gear all its own; for instance, a Bosun's Mate must be equipped with knife, lighter, and marlinspike at all times. This is just the same, except there's only one MOS throughout the entire force.

I recently read Seven Eves by Neal Stephenson. Potential spoiler:

Combat in that universe takes place mostly in space habitats. Conventional weapons are not ideal in that environment.

So they developed a kind of weapon that shoots tiny robots that avoid penetrating habitat structures. When landed on humans they would crawl around to find an opening in the suits and wreak havoc.

Full body armor could definitely be useful in this scenario to prevent or slow these small robots from entering their suits and bodies.