Jeez, firstly I never thought I would play an MMO where it is difficult to get a group as a healer. It shouldnt be possible, but it is. The Duty finder fast enough and no one uses it because inevitably you get someone that has no business being in a dungeon.
You need some sort of gear lock outs for the dungeons (like in other MMO's) to try and build peoples confidence in the duty finder, otherwise scores of players are going to get board and leave!