They need to have aircraft have time-limited, or limited munitions completely, sure you'll get those idiots who can't fly, let alone pretend to on the ground with their arms out shouting "neeoooww", those people who will waste all the ammo in a second.
Said it earlier though, if you do limit how much or how often they can expend munitions, it could be a good thing for balance.
I know it's a different game but arma has -the- perfect balance system in a military fps with vehicles, as long as you don't start putting loads of vehicles in which battlefield does. I like battlefield '42/vietnam/2/2142 and it goes downhill there for me, it's progressively becoming more tailored to new generation gamers with instant gratification.
But yeah, air vehicles should require the help of ground units to spot mostly, not going around carpet bombing all the capture/spawn zones, then flying over an aircraft carrier to "re-arm" and do it again and again.
What if you only had 2/4 bombs (guided by simplistic spotting, nothing to advanced as this is bf, non guided), 2 aa missles, 2/4 agm, and front cannon. Once they are out, you either need to spend time re-arming, or wait X minutes, both, or similar. But then you'd have to control the spawning of tanks, aa emplacements, etc etc so they don't get free roam.
Edit: Dragging and mounting weapons, woot!
One thing I miss is mounting weapons, is such a large part of shooting a gun! Use whatever is around you to stabalise.
Dragging is great, if the game play is slowed down a little, currently it's a little to twitchy/spammy (rpg/grenades//etc taking down entire building walls too easily)
Right now when playing bc2 I feel that the enemy can come from any direction, no sense of team work, not being able to hunker down and provide a choke point or area of defence, we'll see.