I was a WHM first, got blamed more than DPS, but less than TANKS for failures. The I leveled SMN, I never get any flack as SMN. Not as many commendations as HEALER or TANK by far. Then I leveled PLD, it's kinda my favorite class right now. I think the issue with being a tank is you have to be more alert and ppl tend to expect you to lead. As a WHM or SMN, there were things I didn't pay attention but the tank had to as I found out later when tanking the same dungeons.

The worst thing about being a TANK is ppl either really like me (get three commendations in a 4 party run) or they hate me and boss me around and tell me what I'm doing is wrong. If there is a failure, they always blame me. One time there was an overly agressive WHM, doing HOLY and DPS too much. He died. Then I died. Who got blamed? Me.

Biggest problem is ppl don't co-ordinate well and a lot are in a hurry for their dailies and very impatient or rude. Ironically I find that runs go very well when the party members are all easy going. The negative ppl don't seem to see how a bad attitude and obsession with blame rather than just dealing with a problem is a big distraction...

I think how hard classes are depend upon the player, etc too.