Increasing xp gained by dps classes in leveling dungeons

[Zojha]

Damage dealers in all games with clearly defined roles suffer from the same problem.

More precisely: Every game with enforced roles suffers the same problem.
Even League of Legends had it with the Support role that nobody wanted to play. That increased queue times the moment they implemented a way to queue directly for a role, to the point they had to create an auto-fill option where people get forced into the role to solve it.

People simply play by preference. It's no different in your run of the mill trinity game. The only people you can shove from DPS to Tank/Healer via incentives are the people who were on the fence anyway and they're usually only effective short-term.

There are only two solutions:
a) Make roles not required, i.e. content you don't need a tank/healer for i.e. either faceroll content like PotD or content designed without unavoidable damage like the last boss in Stone Vigil (Hard).
b) Develop a system to dynamically add role slots to parties.
c) Find the magic formula that makes tanks and healers more fun to DPS players and apply it

Those are the options to solve it. There aren't that many.
"Making friends" doesn't solve it one bit, it only shifts the problem around because the total amount of tanks/healers/DPS doesn't change through it. It shortens your queue times at the cost of the queue times for randoms. "Screw you, got mine." isn't a valid solution to anything.

[Arrius]

More precisely: Every game with enforced roles suffers the same problem.
Even League of Legends had it with the Support role that nobody wanted to play. That increased queue times the moment they implemented a way to queue directly for a role, to the point they had to create an auto-fill option where people get forced into the role to solve it.

Because those are roles with responsibility to others than yourself, hence its avoided by the majority of the playerbase - They got enough of dealing with that in the Real World, so why bother with it even in the game?