I hated wow ever since its concept and announcement, I was a huge Blizzard fan before Warcraft 3, but they started leaning towards the cartoony style with it and pushed it too far then with wow, also, the concept of a monthly fee was something quite new and outrageous...
I loved Warcraft universe because I played a lot of War2 with my friends in Lan, it was with Doom 2 the first PC games I played, and enjoyed them for years, so I was really interested, but they had to come up with a rip off model for WoW (level of aggression eleven!) There the spiral of hate began.
Eventually, years later, someone got me to pay a monthly fee for Aion (which I find infinitely more attractive than wow)... so I liked that game... but I still regret having spent my money and time on it, as I found out that all I have initially thought about the concept of monthly fees being a rip-off, was true and not just a theory.
-You get bored and leave the game for a while, then you feel bad because you payed for that time, or in other words, its forcing you to play it, which stops being fun and feels more like a job.
-You stop paying and you can say goodbye to all you've done in the game, never see your character, progress, friends, or anything you did in the game again, nothing you did matters anymore, at least, until you pay again. If you stop paying you will only leave you a sad aftertaste and a feeling of loss.
-Monthly fees are not justified, they don't justify the updates and server maintenance, as Guild Wars have proven that they can offer all that without charging you anything else, In fact, Guild Wars had far better support and more updates than Aion
Another reason to hate wow is the media overload.
I'm not gonna say I'm not gonna fall for one MMO monthly-fee-scam ever again, but I'll certainly do all I can to avoid it.
Still, both Starcraft 2 and Diablo 3 look very interesting (and its hard for me to admit it for all the hate I've accumulated for Blizzard, still... the Warcraft universe remains dead for me since War3, I just can't stand anything warcraft now)