Yes for a little while.
1. Money concerns, gas is more important than MMO's. So is food and rent.
2. Guild and friends took a hiatus and so did I.
3. Needed a break anyway so I could concentrate on other games.
But I did come back recently and have found I still enjoy the game. I can understand why people don't play anymore. The "douchebag" argument to me is a little lame though, those type of elitist jerks can be found on any game. See TF2 free-to-play bias for a great example. Also some discussions here on CoD quickscoping and other play-style biases. Sure WoW has a lot of them, but I've always chosen not to associate myself with those people or guilds that contain a great number of them. My current guild is full of great people, who are open to both casual and hardcore PvE or PvP players that don't have a better-than-you attitude. Its all about how you make friends, not who you meet in random PuG's. Sure I've met my fair share of assjacks in WoW, I've met them here on Escapist too and this just a forum/magazine site.
The issue of nerf-ing/overpowering. In a game that changes constantly, Blizz has to keep up with many fronts; Bugs in the code that allow some classes to exceed their designed stats/damage/healing/mitigation. Exploiters who use everything they can to gain an advantage over other players or just to gain things for themselves without having to work as hard as the rest of the game. Challenge level for all players, not just a few who want everything to be insanely difficult.
Sure Vanilla WoW was difficult, but a lot of that old-school raid difficulty came from coordinating 40 players to work together on raid bosses. One of the reasons WoW seems easier is mainly because of that. People seem to think that if a raid has been full cleared within a week of release that means its too easy. They also seem to forget this game has been out for 6 years and people have been playing it so long that the mechanics of raiding have become second nature for a lot of players and the learning curve is no longer as steep. Its not new anymore, and its becoming tougher on Blizz to design challenging raids that aren't so over-the-top that only a handful of elitist spreadsheet freaks can complete the game. Remember this game in the end is for everyone who plays it, not just the hardcore players. Also they're attempting to make the encounters less time-consuming so players can play together reasonably without having to spend a bulk of their time raiding and nothing else.
Repetition. Every game has this, and every game can become tedious at some point or another. Its all relative to your tastes. Gathering quests I admit are pretty boring. But the Cataclysm re-design of the vanilla quests took a lot of that repetition away in favor of more story-driven questing. Of course there are a lot of cutscenes which some people seem to think ruin games... My only issue is that BC/WotLK (70-80) content now seem backwards after doing Cataclysm (1-60) content, but I'm confident Blizz is working on that to even out the leveling/gameplay.
But hey, if you no longer enjoy WoW, thats fine. There are still plenty of players who do enjoy it. Blizz still gets my money over other MMO dev's because they've made a solid game I still enjoy and I'm not self-blinded enough to overlook that like every other game company out there they are in this for the money. The difference is they do listen to their fans and also encourage feedback (not bullshit whiny rants but actual feedback that has clear and concise language) on how the game could be made better. Feedback doesn't mean rant about how Blizz nerf'd your overpowered class in favor of balance.