Just because I don't agree with their choices, doesn't mean I don't understand them. Even though Sunwell was an unplanned response to Black Temple being "tuned too well", the next expansion not being ready, the top guilds crushing existing dungeons, it doesn't make sense to release content that 5% of your player base ever has a hope of seeing, much less finishing. I mean I get it for sure. From a monetary/subscriber point of view, they absolutely did the right thing, the hardcore crowd for sure was the minority (the vocal minority), but minority nonetheless. I think we're seeing that in the subscriber numbers, 10% of so people got fed up and left, and the remainder are [happily?] plugging along. But playing through the various expansions, you can definitely feel that the top designers, etc have been pulled off onto Project Titan. The game has lost some of it's epic feel (which could also be due to it's age as well).
The way they approached the problems with Sunwell in 3.0 and 3.1 seemed really good. All of the content was easy to finish, but fights like OS3D, firefighter, yogg+1, and algalon were engaging for a long time. After that the hard modes stopped being significantly different from the normal versions of the encounters, which makes them a great deal less exciting. The lack of excitement in high-end raid content should only impact high-end raiders, though, so this probably has very little to do with the people who are leaving the game.
