We need multiple levels of damage, and also to separate some of the damage components. IIRC, both of the 109's oil systems are still linked together. The prop and the engine are still linked together (the prop could have multiple levels of damage, such as pitch being stuck, or the end of one prop being ruined, etc).
The outer wing is still tied to break between flaps and ailerons (would count as both). No oxygen systems for any of the planes. No ability to jam bomb-bay doors. I can't ever recall seeing a bomb interact as a physical object with a plane (smacking the prop if you dive as you're releasing a center-mounted bomb, not exiting the plane (falls back into the bomb bay), etc).
And one other thing that would be cool is if our explosions actually had some physical force to them. HE shell lands under your wing, your plane is blasted up a bit, before crashing down. Bomb impact nearby sends you flying before you hit the wall and die. Carpet bombing causes turbulence for low-flying aircraft, etc.
