Different systems for different cultures would be even more immersive.
But in general i think such a game really needs some sort of it.
In Warband all Nobles seems to be only like "placeholders" ...okay the King and the Marshall had some special role but imo there was much more potential in the system.
As a King I should only have to worry about my direct vassals!
If I THE KING call them for a campaign, it is their damn job to rally their vassals and bannermen...not mine! When it all falls to my competence, for what i have gave these fools their position?
