I do not get why, as in not well this is how they decided, but why is there not a "however if you want just this" decision?

Quality is tied to space age so you can't use separatly.... but tons of mods allow you to do....

this, as well as all the others can't exist in game, even if you own the the DLC, but, mods can add them???

Enemies and regions can also be added into the game, like everything on nauvius that sure enough, does touch the spage age elements and might mess up overhaul mods that will conflict with the space age dlc.

But my main questions is how comes the devs did not implement such stuff as a default feature since the dlc is a paid expansion and not a free mod.