Alot of the time if a modder has good content and such the devs will often times approach them to see if they want a job working for BeamNG Aswell, in the early days alot fo developers made mods on the side too, Nadeox1 being a prime example having made the original crown vic and various other prop mods, so just because it is developer quality does not mean it needs to be in the game Also, downloading the mods off the repo is no hassle, even if you need to do file work, fom where it stands even from a legal perspective, if it is on the official repo, it comes with the game by default (owing to why no copyrighted content can be on the official in game repo) Overall its a good idea but not fully needed
The cherrier picnic would make my list of "this should be official content" Beyond that, not anything I would consider tbqh.