Make achievements for doing things

Guaranteed people will start gearing towards getting them.

For example making something like scout assist where if an enemy is in sight range of you or a plane you own then you get points + a fancy thing
Mr. Scrub will say, oh hey I can earn points with this useless plane?
And then he'll scout with it and send it out for once

Or even something like kill x subs a game and get a cool ribbon that's useless otherwise

ASW EVERYWHERE

It's proven that if you have tangible benefits people will do it.

No exp does not count as a tangble benefit because there are easier ways to get exp than kill subs.