The main reason that this has been brought up now is due to a recent thread on the official WoW forums, where a Blizzard poster actually detailed some of the company's rules (over a number of different pages) for adding the existing and any future premium services. They won't start charging for something that used to be free, and the pay features should be superficial conveniences and not 'integral to the game', ruling out item sales. Another very simple reason that they charge for certain things is to stop players from doing them too often -- no quickie gender-changes to beg on the Orgrimmar mailbox for a half-hour.
This seems to be the right way to go about things for a subscription-based MMO, or at least it has been so far. Leaving aside the debate about the future of the subscription model, would you pay monthly for a game that offered gameplay advantages to those that paid just that little bit more?
