As The Fault in Our Stars barrels into theaters this weekend virtually guaranteed to become a blockbuster, it can be hard to remember that once upon a time, an adult might have felt embarrassed to be caught reading the novel that inspired it. Not because it is bad—it isn’t—but because it was written for teenagers.

The once-unseemly notion that it’s acceptable for not-young adults to read young-adult fiction is now conventional wisdom. Today, grown-ups brandish their copies of teen novels with pride. There are endless lists of YA novels that adults should read, an “I read YA” campaign for grown-up YA fans, and confessional posts by adult YA addicts. But reading YA doesn’t make for much of a confession these days: A 2012 survey by a market research firm found that 55 percent of these books are bought by people older than 18. (The definition of YA is increasingly fuzzy, but it generally refers to books written for 12- to 17-year-olds. Meanwhile, the cultural definition of “young adult” now stretches practically to age 30, which may have something to do with this whole phenomenon.)

The largest group of buyers in that survey—accounting for a whopping 28 percent of all YA sales—are between ages 30 and 44. That’s my demographic, which might be why I wasn’t surprised to hear this news. I’m surrounded by YA-loving adults, both in real life and online. Today’s YA, we are constantly reminded, is worldly and adult-worthy. That has kept me bashful about expressing my own fuddy-duddy opinion: Adults should feel embarrassed about reading literature written for children.

Let’s set aside the transparently trashy stuff like Divergent and Twilight, which no one defends as serious literature. I’m talking about the genre the publishing industry calls “realistic fiction.” These are the books, like The Fault in Our Stars, that are about real teens doing real things, and that rise and fall not only on the strength of their stories but, theoretically, on the quality of their writing. These are the books that could plausibly be said to be replacing literary fiction in the lives of their adult readers. And that’s a shame.

The Fault in Our Stars is the most obvious juggernaut, but it’s not the only YA book for which adults (and Hollywood) have gone crazy. Coming to theaters later this summer is If I Stay, based on Gayle Forman’s recent novel about a teenage girl in a coma. And DreamWorks just announced it bought the rights to Eleanor & Park, Rainbow Rowell’s outcast romance that Kirkus Reviews said “will captivate teen and adult readers alike.” Before these there were the bestsellers (and movies) The Perks of Being a Wallflower and It’s Kind of a Funny Story.

Adult fans of these books declare confidently that YA is more sophisticated than ever. This kind of thing is hard to quantify, though I will say that my own life as a YA reader way back in the early 1990s was hardly wanting for either satisfaction or sophistication. Books like The Westing Game and Tuck Everlasting provided some of the most intense reading experiences of my life. I have no urge to go back and re-read them, but those books helped turn me into the reader I am today. It’s just that today, I am a different reader.

I’m a reader who did not weep, contra every article ever written about the book, when I read The Fault in Our Stars. I thought, Hmm, that’s a nicely written book for 13-year-olds. If I’m being honest, it also left me saying “Oh, brother” out loud more than once. Does this make me heartless? Or does it make me a grown-up? This is, after all, a book that features a devastatingly handsome teen boy who says things like “I’m in love with you, and I’m not in the business of denying myself the simple pleasure of saying true things” to his girlfriend, whom he then tenderly deflowers on a European vacation he arranged.

That will sound harsh to these characters’ legions of ardent fans. But even the myriad defenders of YA fiction admit that the enjoyment of reading this stuff has to do with escapism, instant gratification, and nostalgia. As the writer Jen Doll, who used to have a column called “YA for Grownups,” put it in an essay last year, “At its heart, YA aims to be pleasurable.”

But the very ways that YA is pleasurable are at odds with the way that adult fiction is pleasurable. There’s of course no shame in writing about teenagers; think Shakespeare or the Brontë sisters or Megan Abbott. But crucially, YA books present the teenage perspective in a fundamentally uncritical way. It’s not simply that YA readers are asked to immerse themselves in a character’s emotional life—that’s the trick of so much great fiction—but that they are asked to abandon the mature insights into that perspective that they (supposedly) have acquired as adults. When chapter after chapter in Eleanor & Park ends with some version of “He’d never get enough of her,” the reader seems to be expected to swoon. But how can a grown-up, even one happy to be reminded of the shivers of first love, not also roll her eyes?

Most importantly, these books consistently indulge in the kind of endings that teenagers want to see, but which adult readers ought to reject as far too simple. YA endings are uniformly satisfying, whether that satisfaction comes through weeping or cheering. These endings are emblematic of the fact that the emotional and moral ambiguity of adult fiction—of the real world—is nowhere in evidence in YA fiction. These endings are for readers who prefer things to be wrapped up neatly, our heroes married or dead or happily grasping hands, looking to the future. But wanting endings like this is no more ambitious than only wanting to read books with “likable” protagonists.

Fellow grown-ups, at the risk of sounding snobbish and joyless and old, we are better than this. I know, I know: Live and let read. Far be it from me to disrupt the “everyone should just read/watch/listen to whatever they like” ethos of our era. There’s room for pleasure, escapism, juicy plots, and satisfying endings on the shelves of the serious reader. And if people are reading Eleanor & Park instead of watching Nashville or reading detective novels, so be it, I suppose. But if they are substituting maudlin teen dramas for the complexity of great adult literature, then they are missing something.

The heroine of The Fault in Our Stars finds messy, unresolved stories unacceptably annoying. Her favorite book ends mid-sentence, which drives her to try and learn the story’s “real” ending from its author: “I know it’s a very literary decision and everything and probably part of the reason I love the book so much, but there is something to recommend a story that ends.” True enough, and appropriate to the character, who finds the uncertainty of her own near future maddening. But mature readers also find satisfaction of a more intricate kind in stories that confound and discomfit, and in reading about people with whom they can’t empathize at all. A few months ago I read the very literary novel Submergence, which ends with a death so shattering it’s been rattling around in my head ever since. (If it’s actually a death! Adult novels often embrace ambiguity.)* But it also offers so much more: Weird facts, astonishing sentences, deeply unfamiliar (to me) characters, and big ideas about time and space and science and love. I’ve also gotten purer plot-based highs recently from books by Charles Dickens and Edith Wharton, whose age and canonhood have not stopped them from feeling fresh, true, and surprising. Life is so short, and the list of truly great books for adults is so long.

I do not begrudge young adults themselves their renaissance of fiction. I want teenagers and ambitious pre-teens to have as many wonderful books to read as possible, including books about their own lives. But I remember, when I was a young adult, being desperate to earn my way into the adult stacks; I wouldn’t have wanted to live in a world where all the adults were camped out in mine. There’s a special reward in that feeling of stretching yourself beyond the YA mark, akin to the excitement of graduating out of the kiddie pool and the rest of the padded trappings of childhood: It’s the thrill of growing up. But the YA and “new adult” boom may mean fewer teens aspire to grown-up reading, because the grown-ups they know are reading their books. When I think about what I learned about love, relationships, sex, trauma, happiness, and all the rest—you know, life—from the extracurricular reading I did in high school, I think of John Updike and Alice Munro and other authors whose work has only become richer to me as I have grown older, and which never makes me roll my eyes.

But don’t take my word for it. Listen to Shailene Woodley, the 22-year-old star of this weekend’s big YA-based film. “Last year, when I made Fault, I could still empathize with adolescence,” she told New York magazine this week, explaining why she is finished making teenage movies. “But I’m not a young adult anymore—I’m a woman.”

Update, July 8, 2014: This post has been updated to clarify that the end of the novel Submergence, like the end of many adult novels, is ambiguous.