Right now, being a vassal or owning a fief is quite useless imo. One of my characters is a king, the other a vassal and in both playthroughs, all I do is manage towns and exchange diplomacies with other factions (bare-minimum declare peace and build-up relations).
I also simply hate to talk to an NPC and he/she doesn't know who the **** I am, like... You're in my kingdom/town/castle and you don't know who am. All that grind to grow your clan, gain renown, influence and reputation, to simply be called a stranger by a peasant in your own city/castle. oof