The "every blog and forum post in some way referencing general discontent" is absolutely nothing new for WoW. One of the more entertaining things to do is dig up old posts with people complaining about how blizzard got everything wrong and they are quitting.
We know what casual players want, if only from observing subscriber levels. Unfortunately, those don't come until after the changes to the game have been implemented. They're not "mythical" by any stretch of the imagination. It doesn't really even take long to find them. You probably bump into a few when you random heroics and wonder why the hunter has on cloth and is using BC gems. They're the people who play world of warcraft because they like gnomes, or want to be a troll with a pet raptor. They actually play the game for most of the same reasons that we hardcore players started playing. We just took a much deeper interest in it. Think about how many games you play without looking up how-to. Ever play halo with friends? Smash brothers? Mario Party? Do you ever do poker nights, or meet up with random people at the gym for basketball? Do you go look up how-to guides on every aspect of everything you do?
Most people do not look up guides on how to do everything. And you're right, we don't know how to know what those players want. In fact, judging by the slight defensive tone in your post, I feel correct in assuming that you're under the impression that I find the changes to the game to be inherently negative, and that's not true. I think, like all changes, that it's negative for some players, and positive for others. I also think that Blizzard has been trending towards doing what they can to keep those players they see as the "most reliable" customer base, and I honestly feel they missed the mark slightly by trying to cater to players who will complain regardless of the state of the game.
The reality is that blizzard has several types of players who play this game, and it's not possible to please them all. It's not the blunt and simple division of casual-hardcore, it's a wide spectrum that encompasses everything from opinionated players who demand everything to highly skilled players who have never posted on blizzard forums at all.
In my opinion, blogs/forums are terrible places to see how the general population really feels about the game. In the end, people vote with their dollars.