I don't really like the idea of some of the best looking things in game being purchased with real money, even if they have no effect on my character's power in battle (i.e., no significant stats).
They aren't mandatory, but it can reach a point where you feel left out if you don't also participate. I'm not sure WoW is really there yet, but it's quite hard for me to justify spending any more money on the game than I already do with the sub alone, such as the multiple characters I transferred to my current realm.
Still, it's Blizzard's game and they can do what they want. If that means acting like EAware and shafting the customers that brought you success in the past, maybe that's best for their bottom line. I'll be doing my part to make sure they don't get money from me, if Blizzard gets to that point. However, I'm still in love with the SC2 pro scene and still/again playing WoW. Blizzard is currently not nearly as ruined as Bioware, imo. I still contend that it's a travesty that Diablo 3 got rating bombed worse than Mass Effect 3.