Actually, they cancel their games if they suck. Ghost probably could have been thrown on the market a year ago, but Blizzard wasn't happy with the project. The same thing happened to Warcraft Adventures, they were far enough along in the development, but it wasn't outstanding enough.
I don't dig RTS games and I don't like Diablo style clickfests, but Blizzard is the only game company I know that releases perfect games every time. Seriously, no one is really even close to their quality control. I trust them implicitely.