Rewarding people to try and make them help others is never a great solution they could make more and more achievements with rewards or add tomes and it won't make the queues any easier. It's the exact same issue in every game not just this one. The fact is most people choose to play a damage dealing class so there are not enough Tanks and Healers to go around. Even if they were rewarded more for running low level content there still would not be enough. They are not hiding away denying you they just don't have enough to match to every dungeon. Also with rewarding people you just make them resent new people since the lvl 50 just wants to get done and spam it more for the rewards and has no patience for new people who want to do a full run to get chests.