DPS will remain to be the most played role so long as they have the least responsibility. It's inherent in the design of MMO dungeons.

Tank dies? Group will likely wipe.
Healer dies? Group will likely wipe.
DPS dies? Unless there's a dps check, continue on, rez when able. And because of the quantity of DPS to other roles, losing a single DPS is unlikely to cause a wipe if the other DPS fills in the gaps.

People don't like being the cause of a wipe.

Trying to lower the risk to the group if a healer or tank dies will limit the mechanics the developers can feasibly expect groups to accomplish. While increasing the responsibility on the DPS (so that one DPS down is likely to be a wipe) would push out the players that don't have as much skill at the game.

No, I think the longer queue time for DPS is a nessessary evil.