The trappings of genre fiction—monsters, masked marvels, gizmos, and gumshoes—are no longer quarantined to the bookstore aisles reserved for popular fiction. Horror, mystery and science-fiction books have spread their genetic code to a foreign habitat: the literature section.
To understand why this is significant, it's important to stress how rare genre interpolations were in late 20th-century fiction. In the 1980s and 1990s, serious writers trafficked in realistic tales, simply told. Led by their patron saint, Raymond Carver, American minimalists like Grace Paley, Amy Hempel, Richard Ford, Anne Beattie, and Tobias Wolff used finely-tuned vernacular to explore the everyday problems of everyday people.
Discounting a few notable (and unclassifiable) isoladoes like Toni Morrison, Margaret Atwood, and Don Delillo, our literature unfolded in diners, standard-issue automobiles, and the living room. Even those writers who did not subscribe to a Hemingway-influenced minimalist aesthetic—John Updike, Phillip Roth, Jane Smiley—still wrote about modern-day people in believable situations. In the 1990s, a new generation of writers took this tendency one step further, hyper-focusing on the stark realities of lesser-known contemporary subcultures (see Annie Proulx, Chris Offutt, William T. Vollmann, and Denis Johnson).
There is a point where literary realism is not realistic. C. S. Lewis once wrote that it's less dangerous for a child to read a fantasy story with talking animals than some "realistic" story about boarding schools because a child can know that dogs and cats do not normally talk but it becomes harder to dispute the reality of boarding school headmasters and the like. My friend J. S. Bangs has referred to Eve Tushnet's observation that "realism" is for those who consider their view of the world realistic while the rest of us must make do with genre.
Having grown up with a fondness for superheroes I've seen plenty of people rip on superheroes as not realistic. Art Spiegelmann once opined that he wasn't into superheroes because superheroes constitute power fantasies for children while he had adult power fantasies. Having actually spent any time at all with children would surely disabuse Spiegelmann of this wildly inaccurate generalization. For that matter in her sometimes denounced essay on feminism Joan Didion wrote that 1970s era women leaving husbands and children to break the shackles of traditional marriage to find themselves as painters and sculptures in New York were not embracing the realistic, pragmatic worlds of consenting adults. They were,instead, embracing the fantasies of children. Essays and novels and movies about the crushing conformity of suburbia are a dime a dozen and ironically the critique of suburbia itself constitutes an agreement with the trappings of genre fiction.
If I weren't feeling sick as a dog and needing to write cover letters and resumes for the continuing job hunt I'd write more than I realistically know I can write about this subject right now.