In some 4x games you have leaders that are city managers.  You can do this if FE, but the Champion is always listed as one of the units in the city, so you have to decide each time you have troops passing through the city to leave them there.  If there was some way to designate the champion as the manager of the city, and then exclude them from the list of regular units in the city, this would make the decision to make them the city manager much more meaningful.  There could also be other benefits involved, like maybe some percentage increase on some of their traits that benefit the city or something like that.

I find that if I have a champion that has some kind of non combat benefit I consider leaving then in a city, but I always wind up making them into another fighter, and ignore the non combat aspect of the champion.