Why a decentralized library? It's easy--more kids can browse at once. My fiction books are displayed at the front of the room, using the book baskets that I made last year. But I moved the nonfiction books and my graphic novel collection to the back, closer to my science and math areas.
I decided to make this change in response to my reluctant readers from last year. Many of them would not bring books to class each day, and as a result I would have 6-8 kids browsing for books at the same time. In close quarters, this led to lots of non-book related chatting!
I've had decentralized libraries before, and I've always liked how these lead to smaller groups for browsing, better book talk, and a smoother classroom experience. If your classroom lends itself to this arrangement, give it a try!