The majority of the bigger buildings lack decent interiors making them almost useless to have if it wasn't for the panoramic view from the rooftop.
Even empty apartment rooms would be fine but as of now there is literally no point in having them as they offer nothing but a couple rooms and a flight of stairs to the rooftop, and that's it.
There aren't even that many models, there is only one apartment building, the hospital and a couple other industrial buildings.
Having interiors for bigger buildings would provide more resources for mission making and urban scenarios.