Big time!
Fire actually like, burning stuff. Like a pilot. Basically make the pilot WANT to get out of the plane.
Wing structure strength/integrity compromised (you get a 151 in your wing, manage to hold on to it, don't pull to hard or it'll snap right off).
Control surface degredation due to surface damage/control lines snapping (the latter of course meaning you lose any and all elevator/aileron/rudder etc.).
Realistic engine damage (possibly individual cylinder modeling?), pilot wounds (all control inputs reduced by 30/50/70%, modeling of an actual bleedout rather then the random passouts we have now).
Self sealing fuel tank modeling should be better modeled- if you have a self sealing fuel tank, your leaks should be significantly less serious then an non-sealed system- unless of course you have a 20mm hole shot through your wing.
Speaking of fuel tanks- how about the trail from a fuel tank ends when the fuel does, eh?
Hit sprites that reflect type of damage indicated/matching ammo (small twinkles for .50 cal, big bad puffs for the 20mm, etc).
