Sorry, but that is not all that happens.
You see, it doesn't cost you anything to stay subbed to the game this way, but Blizz gets $20 / mo from that kind of subscription. You may not be paying Blizz, but you are supporting whales, and Blizz ends up with even more money than if you just paid $15 / mo.
You want Blizz to be better? Then you need to break out of the cycle that gives them money for being lazy. Until that happens, Blizz has no incentive to put more effort into the game.
Sometimes it's lack of a true alternative that makes people keep doing something, as well.
Say you're a horny guy, but there are no attractive women left in the world... well... you get to either settle for unattractive women or have no sex. Personally, I'd settle for unattractive women. Same can be said for wow for a lot of people. I played for the longest time simply because there isn't another MMO out there with a solid raid scene.
So you play a game you dont like so you can play a game you dont like for free? Sounds like a serious case of addiction to me.
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At first it seems that way, but this isnt an isolated case - there are numerous other people following the exact same thought process both in game, and on various forums.