Long-time player, I will never buy another Blizzard product. Here's why:

In the beginning, Verant created EverQuest, and it was good (subjectively.) The maniacal, egotistic pricks at Sony bought the rights and made what was once a game for people who wanted a challenge into an even larger grindfest filled with mobs that were extremely difficult to kill and hours spent looking for group depending on your server's population and progression.

Blizzard saw this and seized the opportunity, giving the hardcore an easier route to leveling up, mastering their classes and telling people they'd never betray them the way Sony did with Verant's child. They made soloing viable but not mandatory, grouping viable but not mandatory and pvping viable but not mandatory. Then came The Burning Crusade, which added more depth to each class and enriched the game.

Once Blizzard decided they had sunk their claws in far enough, they released Wrath of the Lich King, destroying the image they had portrayed and revealing themselves for what they truly are; money-hungry pieces of poo. They ruined class balance, added resilience (I believe it was WotLK and if it was TBC it wasn't long before WotLK) and ruined pvp for all but those who could afford to poopsock for days with just the right teams. Some classes remain near useless in pve due to nerfs without the best gear (warrior, warlock) and some are downright hideous in end-game pvp (hunters, lol.)

I don't regret playing in vanilla. I don't regret being a successful guild leader in TBC. I regret trusting Blizzard or any company to actually give a damn about their customers.