I think you hit the nail on the head. Many of the comments on the net blame one group of players or another (bad tanks, lousy DPS, etc.), but the truth is that the Blizzard devs bear the brunt of the responsibility.

By allowing players 1 full year of over-powered steamrolling of heroic Wrath content, they conditioned the player base to the notion of quick, easy dungeons runs for badges. Then they turned the tables by simultaneously making tanking and healing "more interesting", and at the same time tuning the dungeons to require near raid levels of player cooperation. The idea that these factors would greatly increase queues in the LFD system for DPS shouldn't have been any surprise to them.

The truth is, Blizzard devs are now trying to bandage the system to keep the player base happy. No reasonable amount of bribery will takes queue times anywhere near back to what they were in WotLK (unreasonable bribes would of course blow up in their face even quicker). If WoW keeps bleeding casual players (whether they leave to go play Rift, and later SWTOR, or just leave MMOs altogether), I predict that Blizzard will be forced to forgo their design aspirations and swing the pendulum back to casual/easy tanking and healing in the next 6 months.

"By allowing players 1 full year of over-powered steamrolling of heroic Wrath content, they conditioned the player base to the notion of quick, easy dungeons runs for badges."

Spot on, Bodrake. While I do agree in part with Allison that the relative anonymity of the dungeon finder and misbehavior on the part of players both contribute to the current situation, I believe it is this conditioning which is the true root cause of the problem. By the time LK had been out for no more than a year, many players were far overgeared for heroic dungeons. This is the origin of the gogogo mentality, not just from damage dealers and healers, but from tanks as well. Being the shot-callers, overgeared tanks would race through LK heroics at a pace that newer DPS classes were challenged just to keep up. It hardly mattered if they were still looting when the tank was pulling the next group. As long as the tank was overgeared and the healer was reasonably competent, an appropriately-geared DPS contribution would not prevent the group from lazily, even carelessly rolling the entire dungeon. Everybody got their badges with minimal time investment and this remained the norm for the final year before Cataclysm.

Where we differ is in the assignment of blame. Yes, Blizzard developers should have known that making tanking and healing more interesting and heroics in general more challenging would have an impact on the player base. Indeed, they did know because they started telling us so months before the Cata release. They did this because we, the players, asked them to. Look at any of the forums prior to announcing the new expansion and you'll see that players were almost of a single voice in saying, "Make heroics harder, they're too easy." There was only one problem with this: we lied. At least, some of us did.

The truth is that only a fraction of the player base genuinely enjoys a challenge. Many of the others have a ridiculous sense of entitlement, a "gimme mah badges with little to no effort or investment of time on my part" attitude. Many players are motivated not by the sense of self-satisfaction derived from accomplishing something difficult, but so that they can parade around Dalaran (or now Stormwind/Orgrimmar) in their epic gear, on their epic mounts, with their epic titles so that other players can see just how epic they are. This low self-esteem and immaturity permeating a large swath of the player base is not something Blizzard devs can control.

The good news is that many of us were truthful when we said we craved greater challenges. We wanted to scale higher mountains because they were there and were thrilled when Blizzard said they would build them. We heeded the warnings that Cata heroics would be harder and we adjusted our playing style to fit the new mechanics. We broke out of the conditioning of many months of easy LK dungeons. We're still playing, we're not bored, but we are rather annoyed by much of the childish griping. If it weren't for all the players who refuse to listen, refuse to learn, and refuse to acknowledge that the game is not here solely for them, we'd probably be as happy as clams.

I place the lion's share of the blame on the collective shoulders of the player population. While Blizzard could have done some things to mitigate our character flaws, ultimately that's not their job, unless it just happens to coincide with making the most money for their investors. As Pogo famously said, "We have met the enemy, and he is us."