lizzard now has pets for sale to be owned by your World of Warcraft character. Unsurprisingly, there were complaints. After all, if no one complained, the likely explanation would be that Blizzard had lost most of its subscriber base.
But, pets. Ten dollars each for a critter to follow you around and perform the occasional emote. I might be interested in them if I actually had an excess of money, which is about as likely as the aforementioned lack of complaints.
Now, some of the objections to these pets seemed to center around the cost. Others focused on more specifically on micro-transactions in a game already requiring a subscription fee. And then there were concerns about Blizzard introducing purchasable services to give an advantage within WoW.
The problem with the last point is that those services already exist. They're rather expensive and only cover a few areas, but an advantage is provided, whether it's merely aesthetic or for a specific advantage in either a Player vs. Player or Player vs. Environment arena.
For the setting, either the thirty-dollar faction transfer, which changes a character from Horde to Alliance and vice-versa, or the twenty-five dollar realm transfer, both cater to a player seeking anything from hanging out with a friend to finding a better pool of players for an arena team or raiding guild. Given that server populations vary in the quantity of players of a specific type, the potential for change can be rather large. As an example, a roleplay server may have a less active raiding scene, because many players are focused on other aspects of the game, and thus limit their time raiding.
Players seeking measurable advantages can find them in the race change service. The human racial "The Human Spirit" gives a 3% increase to a player's Spirit statistic, which is rather useful to any class that depends heavily on such. Another example, "Taurens' Endurance," provides a 5% increase to base health, which would of special interest to any tanking class. However, the costs of such services may be high enough to limit their use by players not supremely interested in the greatest possible advantages.