Fast Travel immersion
I get putting the fast travel on roofs for quality of life but I think a better idea would be to put teleports at the door of the building on ground floor that zip you to a corresponding door on the roof.
When I fast travel to a street and a bus drives by or Vee makes a bus related quip it feels natural. But hearing that same quip when I have been dropped on a roof doesn't work. I wouldn't mind still being required to climb a new building the first time to lets say "grab an elevator key". After that just rolling to a building, interacting with the door on street level followed by a zoom up to your character appearing in front of the door at the roof would be a cool affect. Also relegating fast travel to ground level and using teleports on the bottom of building will lead to more natural feeling expoloration.