ye, this i also a problem atm you can play only with bear or dh as tank.
maybe we see more in the next addon. another problem is nobody want to take new player because they didnt have xp and maybe more grp will take new players if they cant drop below one of this rating walls.
pls also like Submit Your Questions for the WoW Development Team Here - #1242 by Dinoo-stormrage maybe they will give feedback on q and A