1 - tanks get insta ques, because game design makes tanking harder - they just plain get all the responsibility. Not enough people want to tank. Healer ques arent super fast during leveling.

2 - flexible party sizes based on what's in the que could be a solution. Lets say the ratio of tank to healers to dps is 1:1:3 they could let parties be bigger and buff mobs accordingly. I don't see any rason they couldn't let parties have 1 or 2 more members, and base the composition on who is registered in df. If tanks suddenly became super popular you could have a 3 tank, 1 healer, 2 dps party The problem with this, is it would probably make tanking LESS popular