As others have pointed out already, segregating the playerbase is not in their interests and would easily cause more harm than good. Yoshi-P has said on record that the point of roulettes is to fill queues; dividing them into 3 categories weakens the queues, making them take longer and completely defeats the point of the roulettes. (Which also, lets be honest. The vast majority will queue for al three or whichever of the three has the quickest queues, regardless of what their own self-perception may be, rendering this system ineffective on that front.)

The roulette bonuses are there as payment for dealing with the randomness the roulette will chuck at a player, whether dungeon or player related. There's already plenty of options for people to avoid playing with people they'd have issues with (create a PF, play as tank/healer + queue with a friend as the other so you two control the pace of the dungeon, votekick someone who's not in the mindset of the majority of the group for differences in playstyle, etc.)