This exactly . Until you're paying for everyone else's account you have no business even suggesting something like this. The real world is screwed up enough with this kind of silliness, I sure as hell do not want it in my fantasy worlds. If you don't want to do it, then don't. If you do then do it. The only way to run missions without clueless lvl 50s is to run them privately. If you get involved in public ones then you just have to accept clueless players as a potential hazard.
He is absolutely right, it is a game feature, people who want to "savor it" will do so, people who want to get to the real ships, and the real playing of the game, will go to 50. (So that they can actually use the ships/equipment/endgame real items they should have been able to pursue since level 10)