That would definately add to the game. I don't know if its doable, but cockpit damage would really add to the immersion too.
I'd like to see broken or shattered canopies when you get a pilot wounding, with the wind sound suddenly howling real loud, and maybe smoke or visible fumes hazing things over a bit. Maybe some broken flight instruments. Other times maybe engine damage would throw oil on the windscreen.
These things can really crank up the clutch factor... I hope HTC devotes some resources to it.