I've said this a hundred times and I'll say it again; back when WoW started printing money, suddenly Blizzard could afford accountants and marketing gurus. These parasites are NOT game designers but certainly have a huge impact on the game. Blizz started to rely on metrics and demographic models for content release rather than just making the game great. The core of the gamers were from a creative, but there were always sidesteps in allowing the game to fully grow within each expansion. Expansions are limited to cycles and believe it or not, originally the game wasn't intended to have expansions at all. Marketing wanted boxes on shelves in stores with posters. So poster boy Illidan for BC and poster boy Arfas for WoTLK.
Blizzard hasn't had an original thought since they stopped playing with Zysis. Hehe No, (also yes) all the core have long gone. They took the money and ran. The company was never about making good games, it was always about making money. Make no mistake; any company is about making that money and if they tell you any different, they are simply lying.