Dpsing as a healer is the biggest reason why I find healers fun to play in this game.
I'd fall asleep without dpsing inbetween heals. Even in larger pulls.
It's rather ridicilous tho to say that it's not part of your job, because it sure is in this MMO.
It's quite clearly part of the design of the healer jobs.

If a healer I am running with doesn't want to dps I don't even comment on it, nor do I really care.
But don't give me the crap about how '' it's not my job ''. Healers in this game are designed to be dpsing too. If you want to ignore that aspect of the design then I am not going to give you a hard time about it, and if it's a problem for other groups that are trying to progress then they'll deal with that amongst themselves.
But don't insult my intelligence by claiming that it's not your job and '' I am a healer, I don't dps ''.
At least be honest about it.
If you're not dpsing as a healer then you're not playing it as intended by the developers, it's that simple.
I'll accept it, others won't.
I personally value honesty. If someone is honest with me then I am willing to let most things go, but if they start bs-ing me they invoke muh wrath and I'll explode their face.