Personally I think one of the most neglected aspect of city builder genre is a game focused on modern public transit, walking and cycling.
You can find historical town builders, yes.
And then you have Cities Skylines and the like who go for the skyscraper asphalt jungle where car is literally the king: nothing is accessible unless you can get there in car.
I just don't understand how with all the attention to human life-sized cities there seem to be nobody working on a game about it.