And as to the actual subject header....
Reasonable on the surface, but bad idea overall.
If all fights were 1v1, yeah, perk multiplier wouild be good, kinda like a handicap in golf or a "rating" number in chess.
But what about this:
I'm coming into a fight, thats layered between 5k and the deck. Below me I see a friendly (think it was even a squaddie) getting cornered by a P47, right on the water just off the enemy base. I jump in, calling out to my bud, but dont get there in time and see the friendly blow up. I belatedly close the gap, fire away, and as I pull up I find that I've killed YUCCA.
YUCCA is a far, far better pilot than I am. 1v1 there wouldnt even be a fight, it woudl be a schooling. I didnt deliberately cherry him, I was doing the team thing, but I was almost embarassed to have killed him. Did I earn any bonus perks for killing him? Did I outfly him? No way on either count.
Now add the problem perk planes have, of getting swarmed because they stand out. How would it be to be hunted while you're trying to get a good fight? To have 3 friendlies on the deck, and find the 1 attacker ALWAYS goes for you because you are the Vet?