I would like to make a correction:

Most people don't care ENOUGH to warrant pointing anything out or potentially starting a fight and prolonging something most people would rather finish in a short amount of time.

Although I main healer (and I do personally love DPSing as a healer), I've been going as BLM as of lately, and most healers I've been teamed up with don't do damage. Now, I don't necessarily like this healing playstyle... but do I wanna be arsed with having to stop what I'm doing to be snarky about it? No. Do I wanna kick someone who might not be performing as I THINK they should and risk party disbanding and having to queue for another 30 minutes? Most definitely, NO.

I'm more likely to roll my eyes and keep going and toss my commendation somewhere else, if I'm being honest :P

What bounddreamer said is right, though. You can't conclude something like "people don't care about healer DPS" from a dozen dungeons... specially if they were from leveling roulette (OP didn't specify which roulettes, I'm assuming they did all daily roulettes for a couple of days).

As for the reason you say it took only a couple of minutes longer... well, there could be a number of factors affecting this