One of the most important lessons I was forcibly reminded when killing heroic Yor'sahj this week was that dying makes you useless. Even if you can be given a battle res, that's not only lost damage time for you, it's lost damage or healing time for the person bringing you back from the dead. It means that battle res won't be available for a tank as the fight progresses, it's just a big mess. This was further reinforced by our Ultraxion kill. Killing Ultraxion on heroic means not only does everyone need to hit a minimum DPS threshold of about 33k sustained throughout the fight, they need to do this while performing nearly flawlessly on Hour of Twilight and Fading Light.
Having tanked the past couple of weeks, it was a lesson I needed to relearn. DPS players can't rely on being the target of a dedicated healer -- there's usually two or three healers at most in 25 man raids (and less, perhaps just one in 10's) focusing their attention on the raid as a whole. Even if they break the healing up into assignments and don't deviate, there's still several people at any given time needing the healers attention. While they certainly usually do their best, if we don't help them out we're only hindering ourselves. The days of 'meh, they'll heal me through it' are long gone.