But...I...I don't wanna DPS, I'm a healer...

[Shurrikhan]

But...I... I don't want to dodge. I'm a DPS. [One-shots exempt.]

Seriously though, you should be using whatever resources you have, be it excess mana, free time, or comparatively high-execute-potency attacks. To not do so is no different than if a tank decided not to pop CDs or a dps decided to take a break mid-fight. You may see it as "out of role," but in the end, it's all just party output. Tanks both mitigate (resulting in less healing necessary) and dps, and DPS, by killing enemies, essentially have no choice but to cause overall mitigation/reduce total healing needs. You heal damage, absorb damage, deal damage. It's really... all... damage. Figuring out the best way to optomize output vs. resource is what makes you able to clear things faster, which, like it or not, is the only real measure of success available. Their are no pure roles, even the healer, but instead only classes with, say, reliable healing spells and whose priorities fit that fact. And that's where a lot of the fun comes in. Know your party CDs, and know when you or your tank can go ham. It's a fun trade of allowance of power, that makes you feel not only more than just a heal bot, but more than a single player/character.