Paladin and Druid tanks have a mechanical advantage in five man content. I don't deny it, and I actually think that it was a vital move on Blizzards part in shaping the tanking scene for the better.
Hang with me - this is neither a rant that warriors need buffing, nor one that paladins/druids need a nerf. I promise.
Coming out of Vanilla WoW, Warriors were the most popular tanks, by far. Warrior and Tank were nearly synonymous for the large majority of people. Sadly, however, the supply of warriors for tanking did not meet the demand of the community. Action was needed.
Burning Crusade revitalized the Tanking side of Feral Druids, and the Protection side of Paladins. The problem was, who would believe that? Now, I'm willing to wager that most people remember the first time they ended up in a group with a Druid/Paladin tank, in a 5 man. Scepticism was likely high, but results were likely surprising. These early Druid/Paladin tanks were largely made up of players who knew they were pioneers, and that they really had to work to prove themselves as tanks. To build on their drive to succeed, they were given the tools and talents to succeed in BC dungeons, which were partially tailored to them!
Whoa. Could that be true? Lets take a closer look.
Paladins and Druids were given abilities which help them multi mob tank, something that proved a huge boon in five man dungeons where the trash often outweighed the bosses, and helped them dispel the lingering myths that they could not be effective tanks. If they were only able to perform "as good" as warriors in these early dungeons, Paladin/Druid tanking may never have caught on. Why would people challenge the status quo?
Warriors traditional strength in single mob tanking was challenged by these large groups of monsters in BC five man dungeons. Good warriors took this in stride, and used the tools at their disposal to multi mob tank "as good" as a Druid or Paladin. For our long period as all around top tanks, this challenge was designed - not as a punishment, but as a balancing factor. Warriors had the un-hotfixable advantage of historical tanking dominance on our side.
Now wait - Didn't I say this was not going to be a rant?
It isn't. Starting right with ten man dungeons, tanking levels out. All the way from Kara to Sunwell, tanks of all sorts are used, with similar success. While guilds may still gravitate towards warriors as MTs, the seeds of Druid and Paladin MTing have certainly been planted, and have come all the way to fruition in some guilds. In different fights, some tanks shine a little more then others, but all are viable (aside from obvious gimmick fights). And all tanks have to work just as hard to get the results needed.
In WoTLC, tanking at all levels appears to be completely leveled out. No more mechanical advantages at any level of content are needed to break down misconceptions about one class's superiority over another. Blizzard has proclaimed it wants to see tanks of all sorts in front of every boss, and variance in the MT's guilds choose at all levels of progression. Warriors AoE tanking tools are being improved somewhat, and dungeons will feature less "huge trash groups" like the one in Shattered Halls, which has achieved a certain level of infamy. Paladins and Druids are getting "panic button" abilities to aid boss tanking toolbox.
Will I get to MT in WoTLC? I hope so. But I also hope that I don't feel I have to (as a Warrior), and that it can be a shared responsibility between players of different classes, without game breaking effects throughout the rest of the raid.