In the last few decades there has been a focus on making entertainment accessible for wider audiences. Take Marvel for instance. It used to be assumed that if you were going to consume comic material, you knew all the old issues and ins and outs of the universe. With the MCU beginning, we got good movies that were enjoyed by a wider range of audiences than would have enjoyed just an Iron Man comic line. This picked up steam, and now we have entire studios pumping out comic book movies for the populous to enjoy and pay for. The content itself doesn’t NEED to be good because these works have seen the wider audience and is doing what it can to keep reaching more people while keeping fans happy and satisfied.
YA is similar. It used to be assumed that if you were a “reader” you had enough literary knowledge to pick up thick and dusty books and have the knowledge and insight to enjoy Twain, Doyle, Lewis, Tolkien, and even Homer and ancient artists like him. As the current generations grew, they wanted to be able to enjoy reading without needing to essentially take a refresher college course first.
Generally speaking, YA works are easy to consume and enjoy. They are more refined than teens or children’s series and are able to handle more mature topics as has been said by others here, but also are not as stuffy and tough to get through as Adult/Classics. We can all understand if a passerby is handed “The Prince and the Pauper” by Twain, and declines to read it due to potential reading difficulty or boredom. If you hand that same person a copy of say, “The Last Wish” by Sapkowski, they are more likely to consume the book due to its more modern writing style and just the increased ease of getting through it. Young Adult fills a niche for a lot of people, books that can be grabbed off the shelf and started on easily while also having complex ideas and characters.
I think there are three things that contribute to the YA genre being increasingly used in writing.
1. Young Adult books are more mature than children’s books but are more accessible than Adult Fiction. This has a certain draw to it on its own as welcoming to a large and growing potential audience of new and casual readers.
2. Most writers (yes this is a fairly large generalization) think and talk in “YA style.” When writing children’s books, language and prose usually has to be simplified for the intended audience. On the flip side, writers also mostly have to employ stylizing techniques to their work to keep their work in Adult Fiction or Modern Classic. Casual writing by adults tends to largely fall into YA, at least in my experience.
3. Simply having the genre name of Young Adult makes it appealing to a wide audience. Anyone aged 16-30 could fall into this category, and newcomers to literature can easily look at YA and think “I am a young adult, I can consume these.” Because time ceaselessly marches on, there are ALWAYS young adults that are looking to enjoy a story.
"Only a Sith deals in absolutes"