There's an article that's made the rounds about how adults should feel foolish for preferring young adult fiction over the "real thing". The article has been roundly criticized — me, I only just stumbled across it the other week — and I can see why, as it aspires to make no friends. It has the nerve to tell people that maybe they're cheating themselves out of the pleasures of growing up.
You heard me say it: pleasures. And no, I didn't say growing old, I said growing up. For so long, we've conditioned ourselves as a culture to believe that adulthood is a time of stifling boredom and childhood/adolescence is where the party really is, that all of the really grown-up things to do start at waiting in line at the DMV and go downhill from there through prostate exams and tax forms. If that isn't a misunderstanding of adulthood, I don't know what is.
Anyway, I don't think it's that adults should be embarrassed to be reading YA fiction. I think it's that fiction creators should be worried that YA fiction is more appealing to an adult audience than their own work — that they're losing ground to a more undemanding, more rewarding (if rewarding in a banal way) product.
The problem, as I see it, is that adult fiction doesn't speak to adults anymore. The adults of here-and-now rarely read novels because most everything a well-written novel used to offer them is now offered to them elsewhere, for far less of an investment of effort or time. Small wonder YA fiction fills the dietary gap: it's easier to digest, has fewer calories, and is often vitamin-enriched.
When people want the long-form entertainment of the novel, they opt for TV instead: Mad Men, Sons of Anarchy, Breaking Bad, Game of Thrones — the latter having started as a novel, but the novel itself only now getting major attention because of its TV version. This I find intriguing, in part because some of this material really is very good (Breaking Bad is being praised as some of the best TV ever made, and by people who are not given to hyperbole), but also because while the commitment of time for your average TV series is far greater than for your average novel, the commitment of effort is ostensibly lower. It's far easier to watch a show and have everything poured into your eyes and ears than it is to engage in the heavy lifting needed to have the same story played out on the page.
I don't think this is a new phenomenon by itself. TV has always had more viewers than books have had readers, and John Cage was complaining about "TV-darkened homes" back in the Fifties. But what seems new is how adult, educated readers now seem less interested than ever in the fiction nominally aimed at adult, educated readers. Maybe, then, we need to rethink not only our definition of literature but our definition of adulthood — one that includes being able to savor things like YA fiction without irony or out of despondency. People read the stuff now because they like it, and because being an adult these days allows for such things without the kind of ostracism it might once have garnered.