Brave Bird is common enough. Skarmory, Staraptor, Honchkrow, Braviary, etc.
Aerial Ace is stronger than Fly.
2 x 60 Damage over two turns = 120 Damage, 180 with STAB
1 x 90 Damage over two turns = 90, 135 with STAB.
The missed turn is less efficient. That is a huge drawback and never an advantage. The situations you mentioned are as rare as the turn not mattering at all. Dig is always worse than Earthquake. Fly is always worse than Acrobatics/Brave Bird. Dive is always worse than Surf.