I was in a terrible Haukke Manor group where the tank had awful gear, and didn't seem to undestand threat. I couldn't do much more than heal, and repose. The next run I had a great tank, and dps that cc'd everything - I moved cleric stance to my main bar, and dps'd A LOT.

The best players in any MMO have situational awareness to do what is most beneficial in a given circumstance. Sometimes that might be sit back and heal, other times it might be CC, or DPS to contribute more. It's all going to depend on theplayers in th group, theire gear, skill set, and the mechanics SE throws at us.

I'm guessing there will be DPS races where healing is trivial and every bit of damage is absolutely neccesary... and there will be healer intensive fights where the healer can do nothing but spam heal.