I've suggested similar to this in a few threads in the past where CCP were being accused of "pay to win" and I never played World of Tanks.

Maybe I used vampire magic to steal their "secret" idea...?

Five cents per death. Handful of deaths per game. Handful of games per day. How long do you plan to play Dust? You might find that those cents will begin to add up once you've found a dropsuit you really like and play it quite often.

It's also an issue of ownership. I find getting a permanent, especially custom, paint job on stuff is a really good way to make it feel more like "yours". It's the difference between playing Saints Row: The Third and taking a default character who uses default vehicles, versus customizing your appearance, pimping your ride, and so on. It's honestly a pretty old and compelling video game trope, and they would seriously make bank if they sold permanent paint jobs, especially custom ones, for vehicles and drop suits. Although simply having a wide array skins will do in a pinch.

And the last and I guess most apparent issue is that assigning paint jobs to variant dropsuits means that you'll either need to only have a few colour variants, which is boring, or you'll need to have a huge number of colour variants per dropsuit, per type, per tier. That's an awful lot of clutter. Simply selling paint jobs that you slot into dropsuits/vehicles/weapons would be far more streamlined.