Make helos more difficult to fly, increase the respawn timer but also make their weapons more powerful. Then lock the pilot seat behind a Pilot role (equipped with a pistol and a light SMG). This should make them more effective when in the right hands, and therefore more enjoyable for people who like flying. It would simultaneously solve the epidemic of kids wasting them the moment the helos spawn. The gameplay would be better if there were dedicated pilots and there was a bit of a learning curve to flying. The same should be true for tanks, of course.