Sadly... There should be reasons where it should be possible without problems. As I said... The banishment of Henry the Lion was legitime and all accepted it.
You can't I believe, you can only revoke tyranny-free.You should be able to banish landed people who has revolted against their liege. Numerous historical occasions that this have been done without angering other vassals.
/Quisition
The problem here is that this is meant to be a strategy game. People often complain of having "nothing to do" because they already conquered the whole world by 1100
By making it more difficult to do that you get more game to play and can enjoy endgame mechanics and technologies
You get more play time and more fun and assuming that it will be much easier to hold together a multicontinental empire by 1300 you'll still get your world conquest