The most obvious answer to your question is lifting capacity.
At the end of the day, with the exception of drones that are designed to be as small as possible while lifting a set weight (usually a camera), aircraft are designed and built to lift as much as they possibly can. The point of that is the same reason that cargo ships are getting bigger and bigger now that cargo has been standardised around the shipping container; carrying more units means that the fuel and time (read as wages for crew) required to do so is spread across more paying customers, or at least more freight. This is the reason for planes like the Airbus A380; if you have enough passengers per day to fly two (say) 747 jumbo jets to the same destination, then ultimately having a single plane that can carry them all makes sense even if it uses 150% of the fuel as you're still doubling the fares you can charge and you only pay for one air crew on a single flight.
To that end, meet the Lockheed Martin LMH1, a prototype for a new range of heavy cargo airships. According to the article, this prototype can carry 20 tonnes of cargo and 19 passengers, but future models could be scaled up to carry up to 500 tonnes, albeit with 800m lengths.
The fact that a company like Lockheed Martin is investing in large scale airships even as proofs of concept tells you that there is a commercial benefit to these designs. If you're moving cameras around, then going small makes sense. But these things can carry (say) massive amounts of cargo through impassible terrain for instance to supply people cut off by floods, forest fires and any other manner of natural disaster. For that reason alone, it seems like a good idea to go large on airships.