Blizzard can't force someone to play something they don't want to play.
It's like if one of your products required a man at a specific lever, but a customer calls and complains that no one is at the lever. It's not YOUR fault that no one is there to operate said lever, and you can't force anyone to man the lever to make it work. The only thing you can do is say "Too bad, you need to solve it yourself."
If millions of people said "Hey, we can't man this lever", then a good company would say, "Okay, lets re-think the lever and how we can get it to work for everyone."
There are solutions out there. Blizz is a smart enough company to figure it out.
But the lever is RIGHT THERE. there is no reason for anyone to not want to pull it except no one feels like it. Your customers would be complaining because THEY didn't feel like taking the necessary steps to solve the problem.
The whole reason behind 45 minute queues is that people are bloody LAZY. No one wants to take up a leadership role as a tank or the the responsibility of a healer. Everyone wants to play DPS because they don't have to worry.
Did the tank just die? Oh, it must be the healers fault. Lets curse him out and votekick him even though the tank was standing in three forms of fire and 2 of the DPS were tanking adds.
Adds are running loose? Must be the tanks fault. It doesn't matter that all three DPS were attacking different targets, lets just quit and let the next batch of DPS/heals deal with him.
But what happens when spells arent interrupted, adds aren't CCd, and the boss doesn't die fast enough? It certainly wasn't the DPSers fault, even though that's their role in the group. Obviously the tank and healer weren't geared enough to survive the encounter. Lets votekick one of them and then leave on the next wipe.
You see, DPSers in general believe they have no responsibility, only an entitlement to the rewards of the dungeon. And most groups only exacerbate this problem as the tank is usually the one to blame the healer, and the DPS just sides with the tank. No one bothers to blame DPS players and this leads to the role being very stress free compared to tanking and healing. It's naturally more appealing and the only way to counteract this is to make DPS play a bigger part in team dynamics... Which is exactly what Cataclysm is doing.