As a tank, I used to always recom the healer in parties, but that was for lv 1-49 dungeons. After 49, you have to impress me to get my recom, usually a dps does a far better job than the healer and they get my recom. Just because you are performing your ROLE, doesn't mean auto recom, your role is a healer.
I don't expect thanks or recom simply for being a tank. You shouldn't either for just being a healer.
I think most people are like me, because on my SMN I usually get 2 recom per run, I have actually seen 3's as well even in PoTD. Something I have never since as a tank, 3 recoms.