Warfare
I don't want a game with a lot more advanced warfare. Really, all I could think of that I would like is maybe some sliders where you could adjust the composition slightly. This to make troops more unique really. All rulers have the same composition. I don't want to micromanage warfare a lot more.
Well, thats your preference, I will stay with mine.
From my perspective, CK2 warfare is showing its age. Terribly. With its gamey tactics, boring sieges (when Europa Universalis IV already rewrote them; note I am NOT talking about Zone of control), ancient naval operations mechanics (note I am NOT talking about naval battles).
Diplomancy
There is a lack of diplomacy. True! But what can't be fixed on the current platform, if unlocking the DLC dependecy situation CK2 is in? It´s not tecknical limits at least.
We
don't know technical limits, that first thing.
There are conceptual limitations. Things that our design allows or does not allow. Looking at Conclave (which was the only try to rewrite diplomacy) I truly doubt we can get good diplomacy model.
Economy
Same as diplo really. What can't be done on current platform?We have seen mods with sofisticated enough economic solutions, or not? Dependency to The Republic and Horse Lords DLC.
Mods are not an answer. Mods are written for specific target in the game target, game is written for its whole target.
Economy is based on vassals. To change economy means to change vassalage system. And this one is core mechanics.
Familly matters
Can as well be improved on current platform. Problem is, evereything that exists on the area is locked behind Way Of Life and Conclave DLCs. But there are stuff they could easely add as branches of dynasties, familly perks and feuds and loyal dynasties etc!
Score system is based on
lack of dynastic branches. Adding branches means all hard research done for historical dynasties goes to trash can.
As for family ties, Its one of that ideas I just cannot stand. In CK2 smallest playable entity is
character, not
family. If there is some kind of four-sided civil war and some guy kill your father, allowing you to claim throne and de facto win civil war (after some clean-up), why should you gain feud against that guy?
Investiture Controversy
I don't see exactly what you meen with this, but sounds easy to add events, politics triggered by pope to gain control over bishop nomination? There should be ways to fiffle with these nominations for all religions without having to revoke chuches. Please tell if I did not understund you correctly.
Overdependency on events is black death of this game.
I believe noone can say better what investiture controversy should be, than devs themselves:
https://forum.paradoxplaza.com/forum/index.php?threads/five-years-of-crusader-kings-ii.999683/ (at the end of the post).
Can it be done on existing design. Probably. If you give pope much stronger agency, de facto making him one of the strongest and most unplayable characters on the map. And if you rewrite how non-teritorial relations works. And how territorial relations works.
Normandy problem
Guess this has to do with the recurring request of having multiple lieges? This can be partially fixed with that king of France get a diplo towards king of England to demand some kind of tribute compensating for Normandy is out of the realm. Does not solve the bordergore but how to solve that in a way that a player would understund from watching the map? Is this not some kind of "Special deals" that has happened thuthout history that is impossible to make rules of? I would very much like to see a proper solution to how this could be implemented - even a roughly one would do
Overdependency on events is black death of this game.
Normandy cannot be solved as special case, for the single reason its not special case. What if some random duke somewhere in the world inherit kingdom and go independent? What if Normandy never took control over England and stay French vassal?
No. 'Dont use events where you should use mechanics, don't create exceptions where you should create rules'.
Crusades
Well again - I see no technical limitations to greatly improving how Great Holy Wars work. Do you?
Yes, at least one. Too much dependency on land (understood as land belonging to the Crown, either directly or through vassals). So award for winning crusade have to be land. So you cannot really create independent Kingdom of Jerusalem, as it kinda happened historically.