I definitely dont think Dick needs a city to protect. Not every hero has to be stuck in one location.
I do think he needs a home and a neighborhood of his own though. Even if it's just where he goes at the end of a mission, he needs that sense of "grounding." Besides, it's one of those things that an A-list hero is supposed to have and even if Nightwing isn't the type of guy to hang about one place, he still needs somewhere to hang his mask.