I agree with the first paragraph especially. I think a majority of the burnout is how we, as players, have reacted to the game itself. Things started getting convenient, and we pushed for more convenience. Dungeon Finder has made the game impersonal, and heirlooms have made leveling more of a inconvenience to reaching level cap instead of an adventure.

The burnout I'm seeing has to do with difficulty. Not that the current raid content is particularly hard, it's just not easy and thoughtless anymore. My guildmates have become complacent and refuse to learn how to best play their classes. Instead of practicing and gearing in heroics on their mains, they level more alts and perpetuate the cycle. Now we have a guild full of people who constantly want to change their mains because their main's class "sucks" or "got nerfed."

The evolution of the game is constantly making things more convenient, and as a result a lot of players have gotten lazy. With the massive changes in playstyle since Cataclysm, people are tending to get frustrated instead of adapting and pushing through.

Personally, I'm having the most fun with the game right now, and I've been playing continuously since launch. It's a game. If you're not having fun, you should probably take a step back and weigh your options.