Nah, if I pay for the game, I should get to keep it. If it's a monthly subscription only (not sure the current state, but WoW didn't us to be) then there's an argument to be made here that I was just buying access to those servers. But if I've plopped down 70 bucks and you don't feel like running your backend anymore, then the least you can do is provide the tools for others to do so.