What would YOU like to see in Europa Universalis IV?

[neondt]

I know what I don't want to see:
Crusades
Automatic Holy War CB's
Wars declared with no CB at all

These things are overpowered both in the hands of humans and the AI (looking at you, Castille), and inappropriate for the time period (at least for European Christians). In EU3 they dominate North Africa and the Levant in ways that make my eyes bleed.

Aggression wars are bad because it results in random countries getting provinces all over the world for no good reason. I like the way CB's are handled in CK2, but they should be a bit more flexible for EUIV - warscore should let you take a little more than is strictly defined by a CB, but not much. You definitely shouldn't be able to annex half of France using a Trade War CB, but taking a few colonies is entirely reasonable.

 

[neondt]

I'd like an improved vassalage system. Maybe make AI vassals revolt occasionally. It seemed quite arbitrary that France in EU3 had loads of vassals while Burgundy was a single huge blob (making, for example, Holland unplayable from almost all start dates). I think feudal (i.e. not absolute etc) monarchies should have something like a "demesne limit" (based on the monarch system thing), giving them large penalties if they don't create vassals.