Y'see, both of those disincentives Dukes from going to fight beyond his Duchy or realm borders. In effect, if he stays at home more and does courtier-style work, his regions will do better and more Lords will be inclined to switch to him to take advantage of a Duke that isn't fighting with a realm's main armies. It does, however, give a fairly legitimate reason for a lord to change if his Duke is just sitting in his city, all day, every day.
Just a thought.
Finton.