Books are not as they used to be.

- I liked this book, but there's too little diversity! It feels like there are only tall and fit beautiful hetero white people. That's annoying!"

Growing up, this remark would have never crossed my mind. It wasn't even something I'd think about. Diversity wasn't even an issue. There was little to no PoC in the novels I read. Main characters usually had the same body type and their sexual orientation was never a question.
But today, young adults have so many titles to pick from that they can actually get a more diverse set of characters and heroes to grow up with and be inspired by.
I find it impressive how young adult literature evolved in the last ten to fifteen years. The number of readers gradually increasing meant that publishers could sell more books and that brought more diversity to the readers.
But for that to happen, it means that writers got the opportunity to write different stories, different characters, and as a writer myself, I find it incredible.
Writing diverse characters isn't necessarily self-evident when you grew up with heroes that all looked the same. It takes some work and some acknowledgement to make one's writing more inclusive.

The fact that kid can know grow up with characters that look like them, who can help them figure out who they are and who they want to be is so important.
Young adult literature is so important!