You couldn't have hit the "bigger" problem better. DPS need to understand that most tanks and healers understand their limits. I recently ran with a pug who needed a healer when our's got DC'd. I was at the time specced as a boomkin for dps, but knew that I could heal Nexus and the Old Kingdom. One of the DPS insisted that we do Nerub, and I said I cant keep up with all the poisons on the first pull as a boomkin.

After we ran the other 2, they decided that my healing was good enough to do Nerub and got our asses handed to us. @ of the DPS then accused me of not trying hard enough and left.

Lich has completley ruined strategy in the game because everyone wants to AoE. I know there have been tons of posts on here about the lack of healers, but I, personally, think one of the problems is there are no hybrid healing specs anymore because you need to be a true healer for instances with the sloppy AoE that everyone has fallen in love with. I leveled all the way to 70 with a DS/NS build and grabbed the one point for boomkin so I could actually level with some ease. I never had a problem healing any regular up to 70 where I went full resto, but now with the lack of CC or intelligent DPS if the tank does try and CC based on my build makes it nearly impossible.

As a tankadin, the first thing I tell the healer is that we are gonna AoE things down and if a pull is sloppy and they don't think they can keep up to tell me and we will CC, and that the first bad pull is on me and I have a lay on hands to save my us, but after that we will CC to make everyones life easier. Almost always the healer says we are fine, but if we aren't they know we wont be b4 the first pull.

Good healers and tanks know their limits, the DPS have got to learn to respect that again.