Ghostcrawler has written a post on upcoming tank changes in WoW. The changes can basically be broken down into two items:
- Tank threat is being significantly boosted, to the point where tanks can maintain threat leads with minimum effort. This is coming in a hotfix soon.
- The tanking classes will have some of their survivability changed from passive to active. Basically, moving towards the Death Knight model where the tank uses Death Strikes at appropriate times to stay alive. This will be implemented with the 4.3 patch.
In the past, tanks have had responsibility for both threat and survival. And yet, survival has always been the most important. I don't think that--in the history of the game--there has ever been a time where tanks sacrificed survival for more threat.1
So this change is basically Blizzard throwing in the towel after 5 years and saying, "Well, you tanks don't care about Threat at all, so we're going to stop trying to force you to care." Instead, tanks will have to take a more active role in their survival. They will still gear and optimize for survival. But if, for example, Shield Slam has to hit the enemy to boost your armor, then stats like Hit and Expertise become survival stats instead of threat stats, and will be valued higher as a result.
Additionally, this will make it easier for under-geared tanks to group with geared DPS, which should help out Dungeon Finder groups a little.
The truth is that tanks never really had to care about threat, save at the edges of progression content. If a DPS pulls threat, most people consider it the fault of the DPS player. This change is merely reflecting that reality.
1. Possibly Horde-side Vaelastraz back in Vanilla, as the Horde didn't have Blessing of Salvation then. But I don't know for sure. I do know that Horde tanks were pretty sick threat machines compared to Alliance tanks in my experiences back then.