Frontline balancing is actually way way better since people were allowed to que as one class and then switch.

What you might be assuming is that the game ques up a balanced match and then people mess it up by switching. This is pretty much mostly wrong.

Mostly the game's match maker doesn't seem to know what makes a match balanced or not in terms of jobs. Healers have always been strong and you need a good number of them, roughly about 2 per 8 man party. Melee are really strong right now in that it's a lot easier to be really good with them than ranged.

So mostly, switching allows people to balance out their team a lot more in practice and that's what they tend to do.