I was talking about this recently, with friends, and it seemed to us like a lot of the problem abilities were added or altered in Mists. For example, while it's less of an issue in PvP now than it was at the start of the expansion, the addition of Stampede for hunters was made in Mists. Symbiosis, the convoluted, complicated druid ability, that grants powerful abilities to other classes was added in Mists. Gateway, the warlock ability that served to make 'locks nigh-indispensable for your raid team, along with their other utility of course, was added in Mists.
Now, I'm not talking about reverting every change made. Monks are cool, for example, and there are several alterations that do work, and fun new abilities that really fill needed gaps for certain classes. But we know the squish is coming, and is much needed, and I'm wondering if we could, for example, put everyone's CC back how it was in Cata. Lose the 87 abilities, ditch the 90 talents and start again, make new ones. I certainly don't play every class, but cursory discussions with WoW Insider writers indicate that they wouldn't be averse to such alterations.
So what would your thinking be on your class if everything went back to Cataclysm, as far as abilities? Is there anything that you consider utterly vital to your rotation or playstyle that was added with Mists? I can think of one immediately -- the level 90 Elemental Blast that my elemental shaman's single target rotation feels incomplete without. But other than that I'm kind of struggling when I look at 87 abilities and 90 talents particularly. I can't pretend to know all the intricate details of minor changes for other classes, but you might.
And I'm not saying for a second that we shouldn't have level 87 abilities or level 90 talents, or even level 100 ones. I'm just saying it should be deleted and they should start again, with the damage some of the changes have done in Mists borne in mind. But there are some things I would change. For example, most classes got some manner of extra CC in Mists. Maybe that should go. What 87 abilities are worth saving? What 90 talent tiers are so balanced and perfect that they should stay just as they are? Personally, I find it fun to think about these things. Maybe you do, too!