The circling makes air units behave much more unpredictably compared to ground units. I can park ground units in strategic locations where they can hit some enemy units or structures without being in range of enemy defenses. I don't feel the same about air units (unless I am doing something wrong). When given a target they attack and then fly far past it and almost always directly into enemy air defenses.
Real world pilots are smart enough to attack and evacuate from ranges/vectors that avoid enemy air defenses. Why aren't hyper complex post human constructs able to do the same? Far future technology should also allow air units to hover at altitude.
I think it might be more fun if air units behaved more like Starcraft where they can be strategically placed to avoid enemy defenses. That or improve the AI to actively avoid flying into enemy air defense zones. For example it would be great if the flight AI would attack and circle around but *never* go past the unit they are attacking relative to their original position to start the attack run.