You know what killed it for me? The way they made epic loot mean absolutely nothing. Getting a 'purple' was an achievement at one point - now it's just given out like sweets.
Take this for example.
This epic plate armor of item level 29 goes in the "Chest" slot. Added in Classic World of Warcraft. Always up to date with the latest patch.
www.wowhead.com
You had to kill a hard raid boss and get a rare drop to even bother starting to get it, then you had to farm enemies at the end of a five-man dungeon to get the stitches to drop, as well as farm mats from difficult mobs in the highest level area of the game. It took you a month of planning and effort to get that one purple item.
But now? Press a button, join a random party, kill the first boss, there you go, enjoy your meaningless purple tat.
That was the fun of WoW - the challenge of it, the ability to do your own thing. Now it's a convoluted, bloated mess.