Just recently I entered the newest chapter of the saga that WoW has been for the last 4 years of my life. I transferred severs, and factions, to join a group of friends and in doing so brought my tank to a place where she was not only needed but welcome.
When I first raided, I raided as a warlock. I was a die hard fan of affliction and yet, bowing to guild pressure, became a shadowbolt spammer in Burning Crusade. At 80, I returned to affliction only to be disappointed that I had to work ten times as hard to achieve the same goals. After a time I decided I had hit the cap as far as a Warlock was concerned and looked to changing over to a new class. I had acquired my second account by this point and so set about leveling to 80 with a shiny new Death Knight and Priest duo. The Priest simply followed while my Death Knight ripped everything to shreds. It was quite simple, after all the DK was more than over powered and only required the occasional heal. Once the duo reached 80 I entered the wonderful world of raid healing with my Priest. So this is the point where I feel I am finally able to outline the differences between the three roles.
DPS is very simple. Target the tank. Target what the tank has targeted. Kill it. With a few exceptions or special case fights where you attack other things, for the most part this is how you raid. Stay out of bad stuff and kill the big thing. Specs, rotations and cooldowns aside, you generally use a select few of your major class skills and kill whatever it is that needs killing.
Healing is much harder. You have 25 targets and have to keep all the green bars as far to the right as possible. To be fair, it is a very difficult thing to do and requires a great deal of concentration. But for the most part it is whack-a-mole, especially in a large raid setting. In Dungeons it is a bit easier, with only 5 moles to worry about, most focused on a single player. If people die, you get blamed. However, I have noticed, healers as a whole get blamed, generally not a specific healer. It could be a dozen problems, most likely a squishy DPS pulled aggro or the tank is trying to tank in the wrong presence/stance/spec/gear, etc.
But of the three roles, I have found tanking to be the hardest, most stressful, and least enjoyable.
First, my gear is focused on Defense, so I can never do anything “awesome”. I don’t kill things quickly, I don’t have huge crits. Second, my repair bills are outrageous. DPS and Heals can avoid being hit and thus their gear lasts longer between repairs. After 3 heroics I have a 40g repair bill, without deaths. Third, it is apparently my job to save the stupid idiot who didn’t watch where he was going and aggroed a second group. These are very similar to the DPS who are so focused on being the top of the charts that they ignore the threat they are producing. The worst of these will blame me for *not* producing enough threat, even though they have top tier gear and I have gear two levels below them. If I die, the healer isn’t blamed, I am.
It really comes down to the fact that DPS can hide in a group of 15 (or more) other people, Healers can hide in a group of 8 (or more), but Tanks… well there is usually only one main tank and one off tank. You have your roles and if you fail, regardless of reason, you have 24 people who blame you. All the focus is on you. No pressure.