Genrefication - help your readers help themselves!
I must confess, I am a genre-aholic. I have my favs (sci-fi, mystery, fantasy) and I always gravitate to those areas at Chapters and other bookstores.
First of all, rather than right or wrong, it's really about what works best for your community. We went to genre spinners for fiction at McRoberts years ago when I was there, and I noticed an immediate surge in circulation. Students do develop preferences, and want to read more of what they like! (Don't we all.)
We can help students discover authors and genres outside their comfort zone by booktalking, creating "these-just-in" displays and promoting exciting authors. (I would never have read the "Adrian Mole" or "Bridget Jones" series if they hadn't been recommended - they don't appear in the sci-fi section!)
I'm not suggesting de-dewey-izing the non-fiction. In some ways, DDC is already genre-ified. (Sports with Sports, Robots with Robots, Dogs with Dogs, etc.) Browsing non-fiction lets you explore a narrow, specific interest to your heart's content.
Is it all or nothing? Some libraries keep the fiction by author, but add spine stickers to genres to help kids spot their favourites. Others only pull out some of the genres (sci-fi, mystery, romance) and leave the rest by author. You need to know your students and their interests.
Krashen talks about the three secrets to becoming a strong and dedicated reader: 1) reading great amounts..., 2) in a narrow interest area..., 3) at your reading comfort level. (link, link, link - especially p5 -narrow reading) Whether we genrify or not, it's all about promoting and supporting an exciting reading atmosphere!
Want to read more about this?
Genrefy Your Library: Improve Readers' Advisory and Data-Driven Decision Making.