I think the more interesting question is "why does grit bother some of us?" There are a lot of ways to approach that question. Take Game of Thrones as an obvious example. (Spoilers ahead)
As a show, Game of Thrones is often violent and "unsafe" in the sense that its characters are always on the chopping block. People die painful, horrifying deaths when we least expect them to. The recent death of Oberyn at the hands of the Mountain is a great example. Most of us who had not read the books had a few expectations: either he would defeat the Mountain, he would die by getting quickly cut down, or he would survive long enough to be killed at some other time. Up to Season 4, I think most of us loyal viewers knew that Oberyn was too good to be true (or too awesome to live). What we got was one of the most gruesome death scenes in the show's history.
here (I can't watch it again... Warning: it is extremely graphic).
Perhaps what bothers us about these instances is a kind of subconscious longing for a fantasy -- not necessarily for a world that literally does not exist (i.e., a fictional fantasy), but rather for a fantasy of action wherein some small piece of the good vs. evil dichotomy is maintained. Game of Thrones consistently shatters that dichotomy. Villains survive while our heroes fall. Villains become our heroes. Heroes become our villains. Everything is gray and messy. Gritty fantasy represents a kind of hyperreal that counteracts our everyday fantasies -- fantasies we maintain for ourselves by selecting what we see, hear, and read (and in a totally meta way, reading/viewing Game of Thrones is a deliberate action on our part). Fantasies about right and wrong, good and evil, life and death. They make up life on this planet.
Let's put our cards on the table, General. You're scared of me because you can't control me. You don't. And you never will. But that doesn't mean I'm your enemy.In the context of the United States' attempts to control who has WMDs, Superman is the ultimate threat -- a veritable bomb waiting to go off in mankind's backyard that nobody can control. And that bomb does go off in Man of Steel. Superman's very presence serves as a flashing beacon that says "super beings can come destroy shit here." And they do. Superman included. They destroy a lot of shit. It's only a natural response on humanity's part to try to determine where Superman lives at the end of the movie. That Superman tries to wave that away by saying "hey, no worries, I'm an American, dude" shouldn't inspire any of us. After all, America is hardly the bastion of restraint.
The attempt to make Superman a grittier figure is, for me, a good thing, in part because Superman is supposed to exist in our world. It makes little sense for him to have developed a sense of morality and justice that doesn't represent a reality that is accessible. But I understand why people disliked Man of Steel and Snyder's/Nolan's gritty reinterpretation. The film performs the same attack on the fantasy of everyday life as Game of Thrones. Worse, Man of Steel shatters the double-fantasy of the comics by discarding the Superman many have come to love in favor for a gritty alternative.
That's how I'm going to think about gritty fantasy worlds from now on: they are not utopian non-places; rather, they are non-places that provide a kind of catharsis.
What say you?