Like i said, dont punish or restrict... Give a carrot, not a stick.
People use pilot kits because with planes now able to engine-die in midair, you want the chance of bailing. So people DO take that kit.
People dont use medics or tanker kits because there isnt enough incentive to do so. I'd rather use an engineer kit than a tanker kit because I can bail and repair the same, I can also deal with ranged infantry, and even take out an enemy tank when I need to bail my tank.
So those kits become redundant. Put them next to a tank wont guarrantee they get used significantly more. However, give them a special ability i.e. internal repairs for instance, or something unique with their binocs maybe, or faster repair or something, and people WILL use it.
you may pick up a limited kit like an SMG, and realize the tank has spawned. you are getting raped by a panther, so you decide to use your spanking new firefly to kill the Panther. Imagine you died if you tried, or you cant enter the tank... That's no fun.
But put a tanker kit next to the tank spawn point and give the tanker kit something special, like slow internal repairs, and you will get the best of both worlds. Freedom, and more use of correct kits...
And yes, there ARE correct kits. This isnt BF Heroes, kits arent just fun variations. They are specific to a task, and there arises correct and wrong, depending on the tactical situation.