Make every roof rotateable. Some roof types depend on their aspect ratio to decide which way it is going to face, but sometimes you want a roof that is wider than it is long but still want the gable to be on the wide side. So just as the slanted roof for example it would be really great if all the other roofs were rotateable too.
Especially the awesome new hollow gable roofs 😉 (although I don’t know how difficult this suggestion is to implement)