I have never thought about the need of acrobatics for flying. Do you ask for acrobatics rolls on basic flying or only if the target is trying a complex maneuver when flying, like attacking?
I have always thought that basic magical flight is easily controllable.
I would say basic magical flight (i.e. flying in a fairly straight line under decent conditions) requires a bit of practice, like learning to ride a bicycle. After all, you are moving by force of intent, not by muscle power.
On the other hand, flying in combat conditions would require a dedicated combat style. And flying in poor weather would certainly require some kind of manoeuver roll, and unless you have a Flying skill, Acrobatics is as good a candidate as any.