Bonuses for limiting yourself?
The game is easy, it needs to add some unrest elements both personally (court intrigue, and vassal modifiers) and on a county level.
Here's my problems, the games great so there's not many;
I don't like culture drift, it makes the game easy. A multicultural empire is an interesting, fun thing and it's historical. It's a little silly when 50% of the map is a Greek Orthodox. It should be COSTLY, and difficult to convert and force a cultural on a people, it should cause wars.
Being a good, king needs trade offs. It's too easy to be this perfect king and nothing goes wrong or tries to take advantage of you because you're loved by all. The more soft (and less tyrannical) of a king you are, the more plots against political power hungry people there are. People need to be afraid of you. Feudalism was not a kind thing.
It seems my family never plots against me, especially my brothers. They need to be dangerous and not so easily manipulated into liking me. Brothers should occasionally flee to other courts, becoming a fugitive after stealing or attempted murder, and try to cause a war against you with an enemy kingdom.
Marrying a lowborn needs political consequences. The AI should avoid to a last resort as well. (May negative events firing off, and problems your children of that lowborn)
For large empires/kings introduce increasingly troublesome events that randomly occur (or in a chain) based on the demesne ( so it unlocks ...)
75 demesne, the sweet spot, occasional peasant unrest.
100, 125. Increasing political problems unless handled by good characters.
150, empire level. National revolts, imperial decadence (may be unavoidable), large bureaucracy bleeding you of money (high stewardship can prevent this), aggressive generals trying to overthrow you (high martial can prevent this), peasant uprisings, religious revolts (high learning can prevent this). Damaged provinces bleed tax money from you
Look to history for problems that large realms had.
If you limit yourself, you can prevent a lot of issues. It's like drinking. You keep drinking and drinking, and things become blurrier and more chaotic and silly. If you limit your personal strength you can prevent a lot of silly events from destroying your kingdom or empire.