Book people are really reticent to change. The books we read today are REALLY similar to the books that have been around hundreds of years. Ever since people switched from the papyrus scroll to the codex books have looked pretty much the same.
Sure, the shape change a little from square to more rectangular, and the material used to make pages has changed too. Printing technology influenced the look of the writing on the page (illuminated lettering is soooo 14th century). But since about the 4th century people have filled their libraries with these stacks of pages, bound on one side, with stuff written on them.
For a long time book pages were animal skins. The easiest shape to get out of an animal skin is a rectangle. That's why books are shaped the way they are. When paper became the popular material for the page it stayed rectangular because people still wanted their books to look like books. Book people are very reticent to change.
Now we have e-books and e-book readers like the Kindle. The high-tech, computerized, electronic way of doing pretty much everything is catching up to the book world. Book people are reacting pretty much the same way they always have: The Kindle is neat, but in my library, I want the real thing.
I have mixed feelings about this new evolution of the book. I haven't had a lot of experience with e-book readers (but I have tried a few). What I have seen has been pretty cool. I would love to be able to just download all my text books and not have to lug 3 tons of bookage to school every day. When I travel, I always pack at least 4 or 5 books. That can get heavy, and with airline baggage restrictions it can be a problem. With e-books, I could just pack one slim little reader and have my entire library at my fingertips. You never have to worry about setting your book down and loosing your page. You can take notes, and search for terms - navigation is much simpler than frantically flipping through pages.
On the other hand, you lose most of the tactile experience of reading when you use e-books. There's something special about actually turning the page (or being able to flip a head and see how much you have left in a chapter). The feel of paper under your fingers, the book smell, the smudges and wrinkles on the paper from various reading adventures are all part of the reading experience. Plus it's nice to have a bookshelf with a display of stuff you read. It's a great thing to peruse at someone's house. It's an insight into their personality.
I could go back and forth about the benefits of both formats, but I wont. I think change is probably inevitable. Like any change, it will take a while for e-books to be really wide-spread. As for me, I'll embrace the codex, but my library is still going to be full of scrolls.