People are freaking out because it's the tip of the iceberg, and because they are already paying a damn subscription fee. Microtranactions are in poor taste because people make monthly payments to put everyone on equal ground from the beginning, and no one wants both for one game, either make WOW micro-transaction based, or based on a flat fee, not both
Also, folks would notice that no one ever threatens to leave a game if micro-transactions are NOT used, and people are nuts if they think it won't snowball from here.
10 bucks for an in-game pet? Geez! EA isn't even that nuts about pricing for a single piece of digital content.