To the people saying you can't possibly test as well as millions of players, well, the designers have some major advantages you're not taking into account, including the ability to do automated testing, and the ability to talk internals with the actual developers who know the weaknesses and corner cases of every algorithm in the game. They would be utterly lazy if they didn't have a version of the game that can easily be played by bots that can try every permutation of every action at every seam, corner, and clip intersection of every map.
Of course, when it's so easy to manipulate people into hating cheaters, companies can choose to be lazy.
Personally I don't care if companies rush and there are minor bugs, but at least have the decency not to whine about players who uncover the flaws. If it's not serious enough to bother testing before shipping, why is it suddenly so serious when someone wins a few online games? I think finding a bug is a bigger achievement than winning a game anyway. Or rather, it's an achievement on a more important level.
And the people cheering on Treyarch, I wonder if you feel as strongly about cheaters who exploit product activation bugs in Windows, Office, Photoshop, etc? Who exploit flaws in DRM so they can copy movies and songs and ebooks?