There's a lesson to be learned from any art, whether its good or horrible.
Sometimes the lesson isn't always explicit enough for us to grasp right away, but its there.
Hatred - Shock value isn't enough to make a game interesting or fun, and doing a hamfisted job of taking the rampage aspect of Postal and GTA/Saints Row + moar grimdark does not equal best game evar. Neither does it mean the end of gaming. It just means that some people have no imagination and no creative depth so they take low hanging fruit. Liking the game doesn't mean you're a bad person, but there are a lot of folks who would probably say you've poor taste when it comes to "what's good". Its not even about the content, its about the lack of anything else beyond mindless murder machine. Does not make for compelling play. One trick pony, and its not even a good trick.
Aliens: Colonial Marines - Publishers will lie to you, don't judge games by their trailers. And its a lesson for devs and pubs alike to not promise one thing, then deliver something totally not even remotely like what you promised. Pissing on the customer base is akin to lighting whatever money you have on fire and hope that it goes out before you're bankrupt and fucked.
Those are 2 examples of bad games and potential lessons to be learned from them. And no one says you can't like them even if they're bad. Just don't expect universal support. But it still has a right to exist.
Slaughtering Grounds - Probably the best example of how to make a poor piece of shit semi-functional and call it a game. Shows me that while some devs/pubs do stupid things, at least they are way better functionally than this digital turd.