I don't think GR2 in itself is the reason barely any mods for D:OS 1 exist, the fact that we couldn't actually MOD the vanilla campaign without some REALLY dirty hax was the primary reason. Some people managed to do that, but it was never a clean modding affair. Doing your own thing was always possible, both for meshes and scripts... but at that point maybe you should be making your own game in Unity instead, not just is it infinitely EASIER it's also much quicker. And those are 2 words I should never have to write in relation to modding a game.
Couldn't agree more, if you are going to make it hard, might as well just make your own game. The main campaign should be quickly modifiable and is what most gamers that like playing with mods expect. Enhancements to the base game. But whatever, plenty to play and do elsewhere. Total conversions we all know are rare and take a lot of time and again, why not just make your own game at this point for some extra coin?