For all the higher-level systems thinking happening in city builders, we never go into the more subtle signals that can make a city feel great or terrible to its people.
Would be cool if we could zoom-in to a specific person in the game, and ask them how they actually feel living here, what they like or dislike about it. Including useless things that we can't possibly fix as a mayor. But that would give us cues to let us figure out what we could improve.
Then once we interview a few of them in a neighborhood, we'd get a picture of what to change to make them happy. We could also have different types of populations and neighborhood for different types of people.
Something more complex and organic than "people in this neighborhood don't feel safe, so you need to add a police station". This would add a layer of discovery and aliveness to the game.