1) Boring/one-sided PVP - why'd they give all the hoard races, pvp based racials, while the alliance got PVE based ones? WEIRD......
2) Instance grinding for Gear... BORING
3) TOO easy - Killing 4-8 mobs at a time all the time, is awesome, but doesn't make for much of a challenge. I used to just chain fight mobs on my Warlock and SP, until my Mana would run out. Eat and do it all over again. Talk about mob farming... BORING
4) Ignorant/Elist people - Far more prevelant in WOW than any other MMO I have ever played. There would Literally be fights in the main cities chat channels constantly.... LAME.
5) WotLK- lol, terrible expansion and what killed WoW for me, other than 1-4.
WoW is no means the worst MMO ever, but it basically brought forth the attitudes of todays MMO players. "I want it easy, I want the best gear and it best be easy to get, and I want to "PWN" mobs easily. It's why harder MMOs like FF11 and possibly FF14 will never do well in the west, SE wants you to earn stuff, western players are against this policy, they want to be given stuff, and WoW is the main cause of this mentality.