Health Pools in Cataclysm
Health pools will be much larger in Cataclysm and healing will be lower. That should help address some of the overly binary feel of PvP and PvE encounters.
You'll still be able to kill people as well as be able to heal them. The pace will just be a little slower and both healing and killing should require more than 1-2 buttons.
Tanking and Healing in Cataclysm
You missed the part where I said health pools will be higher. Imagine a boss that takes say 3-4 hits to kill a tank, but it also takes a healer 3-4 heals to top her back off. Now efficiency of a healing spell can be as much of a consideration as direct throughput, since the tank is unlikely to die in your next GCD. Now coordination among healers can be a bigger deal since efficiency will matter. Now maximum health on the tank classes will matter less because the question of how long you can survive without a heal landing is largely academic. Now avoidance on a tank can matter a little more because saving healer mana becomes as important as being table to take the next hit.
As an aside, healers will actually need enough healing tools and enough distinction among them so that they are really choosing the big, expensive heal vs. the small, cheap heal vs. the fast, expensive heal, to name just a few examples.
Classes balance in Cataclysm and burst damage
The gear scaling is "easy" to fix, meaning we know what to do and it just requires a lot of work. We are prepared for players to be sad when their ratings convert less favorably, but most would agree it's good for the game in the long run.
I already addressed the burst issue above. If the bathtub is bigger, then the rate of health pouring in and going down the drain don't affect the volume as severely.
There is going to be a big focus on BGs for Cataclysm, including the ability to get the best PvP gear from rated BGs. (All of this was announced at Blizzcon -- I'm not saying anything new here.)
I also don't want to give the impression class balance is perfect. It's not. We have some success stories and some specs that we didn't get to where we intended. But we had an ambitious design from the beginning, and the way we work means there is always a much larger list of stuff we want to get done than we can actually fit into a given expansion or patch. We think the trend is good, and a lot of the changes we made for Lich King are going to endure through Cataclysm, which means we'll be able to focus more on the problems we have now rather than resetting everything.
Effective Health and Tanking
Too many of you are using EH (which is a very powerful concept for purposes of trying to decide how to gear your tank) as the number that indicates tank awesomeness. The higher the EH, the better tank I must be. It's just not that simple.
I have yet to see any data that suggests warriors wipe relatively more than other tanks. What so many of these posts say are:
1) I wipe a lot. It must be my class.
2) Because my EH is lower, I am guessing that I wipe more often.
3) I'm not sure if I wipe more often or not, but please just give me a buff so I feel better.
The only argument I have seen so far that seems at all reasonable is that stamina scaling or other factors might eventually lead to warriors (and DKs) having a problem, and that "eventually" could happen in Icecrown. Unfortunately that's impossible to prove or disprove at this stage since it's all speculation. It's definitely something to keep an eye on though.
(P.S. To be fair though, there are plenty of druids worried that scaling will end up hurting them because there is so much bonus armor on plate. They just tend to get drowned out in this particular forum.)