I have to agree with Lutes on this one...
Intent is dang near impossible to determine.
That said, I doubt that 98% of the population are dropping hangars of some sort with the intent to ruin someone's day (except the enemies).
They have an agenda, and it's probably as innocent as anyone's.
In Lutes example with the fighter ignoring the warnings, he probably wasn't intent on ruining Lutes fight, but more likely interested in scoring the kill himself.
That might be greedy, inconsiderate, and he should probably be taken out back and beaten with a rubber hose...
But he probably wasn't intending to ruin the fight (even if it was a jack-hole move). That was just a byproduct.
Unfortunately that can happen with bombers/dogfighters. Bombers want to help the cause, drop the hangars, which in turn might wreck some really good dogfighting. Bottom line though, they probably aren't trying to wreck someone's fun. Besides, as was mentioned, they have just as much right to drop bombs wherever they like, just as you can start a dogfight anywhere. That's the advantage that HTC has set up. The maps have multiple points of contact and there's always another place to start a fight, and those hangars will be back up in 15mins anyway.
On a final note, lots of times if a base is under attack, to take pressure off a squad launches bombers to drop the hangars to give the base under attack a chance to regroup and catch it's breath. How is a bomber pilot to know what the enemy intend to do. Those fighter pilots might think it's just a furball, but someone else might interpret that furball as an attack on a friendly base (which it usually is). As a defensive tactic they wipe out the hangars.
I guess my point is, if at all possible, announce your intentions. Try and help the team out, and don't wrag on the bomber pilots. They are few and far between, especially when you need them johnny on the spot. To say they're ruining your fun, because you were just interested in a fight, isn't fair. The main arenas are all out war. If it's just a fight you're looking for, then the dueling arena is always packed in the donut of death and you can almost guarantee that the hangars will always be up there.