Often not the best option. What your saying is that in WW2 pilots would magicly teleport to another field along with their plane. Planes were rearmed in WW2. If you don't like it then you can never again use "Its gamey" as a reason for rejection of an idea.
Find one example where a pilot landed, asked for
less fuel or ammo, refueled immediately and took off.
Sure, planes rearmed and refueled for a second sortie. If the second sortie was previously planned, they took the time to rearm and fuel as needed (land and replane). If it was "under fire" then, time being of the essence, they probably threw on whatever was available.
Hangers down? Take what you can get, which is what you took off with the first time. You can still rearm. You're just stuck with what you get.
Otherwise, replane.
Maybe if the OP stated
why he wants to be able to change loadouts on the fly I could get behind the idea.
Right now, you can accomplish what he is asking for without implementing what he is asking for.
wrongway