Leader idea

[soibean]

true, but even still
moving the focus away from rome and the republic
If you are Armenia and you have an excellent king... he has good traits and isn't corrupt etc etc. The kingdom benefits. But then his son comes into power, he's a pervert, corrupt, likes to gamble, extravogent etc. Then it hurts the other provinces because he is constantlyl taking from their income and using it for his own selfish desires.
I wasnt looking at the faction leader as a tool for your use for expansions, but rather as a person whose traits play a bigger role in the game.
I used augustus and caligula as examples to show the two extremes, generally your leader should fall into the middle but even so...