Change Support to Healer and remove the message about queuing up as multiple roles being faster until the player has a standard level 8+ of each role. (Or remove it altogether).
It ends up slowing runs down instead of speeding them up because we have Runemages level 1 that are going: It said to queue up as everything.
And so then we have no tank or no healer unless someone want to run the missing roles and so everyone ends up having to requeue (multiple times if the same player(s) keeps selecting all the roles) if nobody is willing to make the sacrifice (daily exp bonus).
While more people might be willing to make the sacrifice if the daily reward was on chest open instead of boss kill, that would probably require too much change on the backend.
One possibility would be to have a brief tutorial on what classes are standard for each role and an explanation that players should avoid queueing up as a role/class they are not willing to play.
Healer: Musketeer or Bard
DPS: Runemage [also Ranger, Scoundrel, and Shaman]
Tank: Paladin or Warrior