Many good points have been made in my opinion.
Like others, I think that not implementing some aspects of CKII's design was a big mistake. While CK focuses on the concrete and personal, EU is all about abstraction and structures. Therefore, it is by definition less immersive and less alive. It feels dusted. It makes a huge difference if you get to see faces in a game or not. In EU, you don't interact with faces, but with "national ideas", maintainance sliders, national stability, etc. etc.
And not only that it is less immersive. In my opinion it is also less "realistic". EU feels a bit as if it has been created by 19th century historians, obsessed with retrojecting the modern nation-state back to centuries where it doesn't belong. Early modern states/monarchies depended primarily on groups of persons, and this is precisely why a person-centered/RPG approach would have been more realistic. The personal element still prevailed over organisatorial-bureaucratical structures, which seem to be the basis for most abstract mechanisms in EU. Also, the "stability"-mechanic cannot even give you a faint hint of the multifaceted and exciting conflicts that took place in (composite) monarchies, primarily between the crown and the estates (groups of local aristocrats). Not even to speak of the complete lack of courts as the theatre where personal interaction took place.
Of course, for a game focused on personal interaction in the early modern period, relationships between persons/characters should not be restricted to what we today would call "private" (i.e. determined a lot by "character traits", like in CK II). Instead, the challenge would be to combine private with political interests.
Some time ago, I came up with a huge wall of text on what such a system could have looked like (although this might have been overly complex):
Brainstorm on Courts, Factions, Nobility. And it's also clear that one would have to reconsider the scope of the game. You can't fill the whole world with characters and agents...
I also don't think that "historical events" are a way to make the game more interesting. I'd prefer to write my own history, a history that emerges from the incalculable constellations and actions of characters in the world.
