ITS NOT APPROPRIATE!!!
I had honestly thought the extra character development would have been one thing to really give this a one up over all other space 4x's.
In pretty much every space 4x, all the races play the same other than slightly different tech and ships (plus maybe a few modifiers on planet types and whatever). Having real, tangible differences in the way the different races politics and culture works (similar to how CK2's do) would have been incredible.
Even without that, having more fleshed out relationships for things like civil wars would have really helped give things a sense of late game purpose.
Hehe. I am not against anything like that, it would be good to have an interesting character subsystem, which works properly on a galactic level. However I am not sure that what should be added [in an expansion]....afterall CK2 had a strong focus on internal politics [rebels, factions, families etc.].
You have mentioned civil wars for example. It can be triggered by an event...yeah it sounds crap, primitive & random, but I doubt that we will have internal politics in Stellaris. It would be awesome to have that, but well...it is a very complex system. We can just only hope that they will work on stuff like this after v1.0. It is possible, but who knows that what do they have in mind. [I say it again: there are more important subsystems in a game like this. If those are "proper enough" they can enhance the game with adding content like internal politics for example.]
PS.
I think they already know that what will be added in the first 2-3 expansions.