The group dungeons are a mess. If I join as a healer I usually take from 1sec to 5min to start. As a DPS it goes forever. The solution would be simple, though. SE would just need to add a 3rd DPS in the group.
Yes, don't worry, it would make things faster not slower. because each healer/tank would "serve" 3 DPS instead of 2, cleaning up the DPS queue faster. Obviously the the difficulty should be made harder and they should give up more loot accordingly.