Personally I liked the feasts from Warband, but I think they can be improved in Bannerlord, if added.
Feasts should only be made in peacetime and would be a great opportunity to meet many lords and ladies in one place. Winning a tournament would grant you access to the feast if your renown is too low.
If you are a vassal with a fief or a king you can hold your own feasts in order to improve relations with other clans.
Aside from that feasts can improve the immersion by adding for example the bards from the taverns and some dancers into the keep.
