As I'm surprised that no-one has mentioned either of these as main factors yet:
Growing things in vats takes time and costs money. Detailed surgical procedures to attach new limbs and organs correctly requires money. Even once things are attached, you will need regular check ups from a skilled doctor and probably physio-therapy as well for appendages which again costs money. Spending all this time doing that will make a dent in your regular work pattern i.e. indirectly costing you money again. Any slip-ups in the procedure may cause you to have to go back to the start of the process and try again.
For prosthetics, they need little, if any, customisation, roll off a factory production line so can be purchased "off the shelf" and are essentially plug and pray. Yes, you might need a doctor of some kind to hook you up but once that's done, the rest is just an occasional lube and re-charge/refuel.
governmentally enforced to be strictly regulated and only for medical purposes as like curing some genetic disease
Although the question states that is for embryo editing, let's think realistically. If I want a new organic arm, do I want the same one as I had before or do I want one that is genetically tweaked to build more muscle mass? How about one that's less hairy or a slightly different skin tone? Maybe I fancy an extra finger? Perhaps an extra joint? Maybe two arms linked to the same shoulder joint? Finger-tips that glow in the dark?
Bear in mind that people have the ability to grow meat in a vat. It's quite possible that people have such a vat in their homes, so they can harvest meat at their convenience, much like people grow their own herbs or vegetables today. By having this technology available in the home, it won't be too long before some bright spark realises that with a little reprogramming, you can use a home meat vat to create other items by changing the DNA seeding.
As soon as people start to get creative, what began as a little vanity for some and a bit of practicality for others will soon be abused before too long and that will result in government regulations as well.
Initially a little regulation to ensure basic safety is a good idea but once people start using non-regulated parts to get around this, the level of regulation will become increasingly heavy-handed. Imagine that the trade in non-regulated parts gets so bad that the regulations state any replacement body parts have to be an absolute minimum of 99.8% identical to the part it replaced and your genetic code. Failure to comply results in the replacement part being removed on the spot without anesthetic, a lifelong ban on organic parts and a hefty fine.
Given that organic body parts can age and deteriorate, this would soon render the replacement body part market an extreme luxury as finding production facilities good enough to ensure regulation compliance for the expected lifespan of the replacement body part will become increasingly challenging and you will have to pay accordingly.
Prosthetics, on the other hand, are simpler to regulate as they can only be produced by licensed factories. The power source/actuator/processor/neural connector from prosthetics gives off a signature that is really easy to trace and any third party tampering will change the signature from the factory one.
Essentially, it's cheaper, faster and less risky to get kitted out with prosthetics, so that's where the money goes. Once portable body scanners start to be issued to undercover police agents as part of the crack-down on non-regulated organic body parts, the above becomes even more true and everybody who gets caught out once will be on prosthetics for life.