So I have never seen such uproar about something so simple that is being added to the game that people threaten to quit or go berserk over something being added to a game. Now there I times when things are being taken out or changed that has made players quite angry. Things like this although I probably didn't agree with them I understand why they may be upset. But adding a feature? Seriously?
For those who don't know what pet battles is. Blizzard is basically adding a combat feature where your non combat pets can battle. Basically Pokemon inside of WoW. There thinking is this is just something else for people to do rather than just standing around. Pokemon something I am not interested in mainly because when that came around I was already pasted those thins. Other WoW players and a lot of them I would think grew up during the craze. Regardless I am not interested in this type of system doesn't mean I will not try it and will not just mess around with it. I probably wouldn't ever take it too seriously, but it does make your non combat pets you have been collecting for years have a purpose. Now this being my opinion here is the argument against them.
Developer time has to be allocated to be spent on different things that people in different interests have been asking for. You can't stretch Dev time to buy three things for the price of one. They chose one thing, and the two other things that people have been asking for have been put off for an unknowable amount of time.
People are upset because the pet battle system is a feature that, frankly, people see as an activity that does not fit in with the scheme of WoW, and feel that the developer time could have been spent on other features that does more for the immersion and assistance for pre existing features in the game such as, for example, guild/player housing or the dance studio.
The issue that people have is that it's such a side niche of interest appeal that it really is something that stands far apart from the other features of the game and could ultimately wind up serving a very small audience that does not justify the amount of developer time that was invested in it compared to other features that could have been.
Now this does sound like a pretty good argument. Lets agree that the dance studio and pet battles are basically on the same level. I think people can agree to that. In regards to guild or player housing I don't see Blizzard adding this ever because it removes people from the community. They don't like how at the moment people are running around cities doing nothing, but waiting for raids and queues. Mists of Pandaria is bringing people out into the world again. So why would they put in a feature that keeps people away form everyone else? They wouldn't.
Now back to the dance studio vs pet battles. The dance studio although they have probably worked on it in some regard would require a lot of work to implement. With that in mind back when Mountain Dew made the WoW red/blue game fuel you could get those in game tank pets that could battle each other. With that in mind, if they already had a basic structure for this pet battle system in place, it may not take as much developer time as many seem to think it would. So they can add a brand new system with minimal coding on their part, and something that will help players pass the time. When you look at it, that is all it is a mini game to help players pass the time. It is not a way that they are slowly changing the demographic of WoW like all the crazy people think.