I'd personally like to see some effect from hitting less than all of one type of building at a field.
ie. Taking down 3 out of 4 fighter hangars should have some kind of affect rather than having to get all 4 down which just totally disables fighters.
Not sure what could happen though. I guess one option would be to limit how many planes can take off from that field at once. So say, for example, i knock down 2 hangars, now only (e.g.) 10 planes can take off from that field and be in the air at the same time. Once one of those planes is shot down, crashes or lands then another can take off. If another hangar is dropped the number goes down, if a hanger pops, then the number goes up.
Or maybe dropping 1 of 4 hangars would randomly disable 1/4 of the available aircraft types? So you could get lucky and knock out the LA7 and spit 16, or maybe you'll just knock out a bunch of hangar queens. Or maybe it doesnt have to be random - could make it set planes per hangar, i dunno.
Similar rules could apply to other building types (ord, troops etc)
Sounds good to me but reading the above speils, i can see the complaints that would herald. Just a thought.