They heal to the extent of what's necessary in this game. Please, tell me how this game has endured for over three months, in every aspect of content, with WoW or GW clerics being unnecessary. If they were necessary, the success rate on -any- content would be severely hampered. That's the real point. No other class can safely res another, apart from Defender. That's a healer.

By that logic we should never get any new content. We've been getting along just fine without, right?

That's too far of a stretch. You're talking about modifying core mechanics unnecessarily, when there are already options in place that cater to the design of the game.