Half of the kids who post on MMoC must not have much experience outside of their bubble. I'll help you
WoW is a game, it is a game created by Blizzard who is now Activision Blizzard. It is a Company, Company's have share holders, what do company's and share holders care about? MONEY! that's right, money.
If WoW has 5,000,000 active subs playing the game and 4,000,000 of those subs don't care about the class system or they mainly care about other features of the game, they are the majority. What does that mean? well it means if blizzard decides to read MMoC and listen to the tears of the minority, they risk pissing off the majority.... less money, which means they piss off the share holders now.
Bottom line... if over the next 5 years blizzard notices that 4,000,000/5,000,000 active subs only log on to do pet battles.... they'll focus on pet battles.
I'm not being unrealistic or dramatic, it's called being logical. Blizzard's main focus is making money, naturally they're going to put the majority of their time and effort into whatever the majority of the playerbase is focusing on, and crying about class balance is the minority in 2020.