I like to queue for 4 man dungeons as a solo healer for fun and have been doing so for years. But, as a human, I make mistakes, and sometimes I end up dead during one of the bosses.
Think of this interaction on the other roles. I die as tank or DPS, 99% of the time I will be resurrected. But if I die on healer, I am beholden to my dps having picked one of the few classes in the game that can rez, or I just get to watch everyone else enjoy the fight. It's even worse in higher lvl dungeons as my team will have the self mit/heals to just drag the fight to the end without me (a fight that is longer now that I'm not there to contribute)
I want to play the game. I don't think it's fair that because I messed up once or twice during a fight that I'm stuck just watching for minutes while everyone else gets to play. Tank and DPS don't have to suffer through that nearly as much as healer does. Yes, there absolutely should be SOME punishment to death, obviously, but would it really hurt anyone if, say, 25secs or whatever after the healer dies and everyone else is still alive, the healer get resurrected? Even if it's just exclusive to 4 man dungeons.
I just can't stand being forced to do absolutely nothing because I made a dumb mistake. I'm not a God at this game, it will happen, and I think lessening the punishment here would do a lot to make the role less intimidating to new players.