Expecting commendations, even when doing a good job, will just eat away at your sanity. I've had the dungeon-of-my-life many time as Healer or Tank (and I'm not slouch on DPS-Healing, or doing what it takes to make runs silky smooth as tank), and sure, sometimes you click 'exit' and not a single commendation appears (and I'd be lying if I said it didn't feel bad sometimes), but having said that, it's just one of many systems out there where it'll boil down more to player choice than it will certain standards.

I see many great posts on the forums but I rarely feel inclined to use the Thumbs Up, for example, just like you'll reach a point in FFXIV where most people just want to get X done and get out to re-queue ASAP [commending people is wasting a precious second of lifetime]. Still, I usually commend people, sometimes because I've noticed someone being awesome, other times because I get a fistful of gil for the weekly commendation requirement - and never if I feel everyone was bad. I'd be hypocritical if I expected people to do more than that for me no matter how good I play(ed).