AI might be the solution to the empty arena(s).
Flying in the Buzzaw map with 50 players (Euro TZ), half in GV's does not cut it for many, and I, and others just log.
There are rare occations when I find a big enough radar bar even there, and when it does, I hit the 'Fly' button.
In other games you can send missions from a field to a target, and you can chose to escort them, or not.
It would bring life to an otherwise dead(ish) arena with too few radar bars worth investigating.
Wirbelwinds are currently too effective in here, maybe it is true to RL (Allied lost close to 1700 fighterbombers in Normandy alone) , but it's just as stupid for gameplay as F3 Lancstukas, for for me and others, they just give an incentive not to hit the 'Fly' button and do something else.