If you do it like that you still need to deal with having lords step down and knights having to leave estates. Having a referendum automatically do that is far less of a hassle and saves hours/honor and prestige.
Ah you mean to an election while a Lord is still present. That is as unlikely as allowing Rulers to force and election for Dukes. These are not rental agreements, not tentant landholders. Once the land is granted it is rightfully the property of The Lord or Lady. If it was not they would not have the option to change Duchy.
