The main reason I dislike them is because what does it teach you? To run around, find guns, shoot people/monsters at random, and try it in real life. Have you seen how many of those games inspired people to go around, and kill people?
I guess, I see where you are coming from maybe, they're still not 100% my type. And yes I've played some. Just, I stick with Minecraft mostly, because it's not overly violent, and you don't shoot people without ruining the original purpose of the game.