For me, books are a tactile experience and designing them is a craft. You can feel them and smell them. They're portable, they don't run out of battery or require a wifi or firmware updates. They're rugged, you can chuck one in your bag or stuff it in a pocket without much worry. They're also a fantastic way of storing a huge amount of information in a small space.
They're not subject to the same censorship laws that visual media is, meaning they can get away with a lot more in terms of content and subject mater than a film can. Look at a film like 'Lolita' for example, which tells the story of a grown man who falls in love with a 14 yr old girl. In the original novel the girl is only 12.
Similarly in A Clockwork Orange, the protagonist in the film is an adult and seduces two women and takes them back home for some of the old 'in-out, in-out'. In the original novel, he's 15 and the girls I believe are pre-pubescent (and it's suggested it's not entirely consensual if I recall).
They're also collectible. Many gamers have dozens if not hundreds of digital copies of videogames, but a large portion still like to collect the physical copies. Why? Perhaps it's because they enjoy owning a physical thing as part of a bigger collection. The Japanese have a word for piling up books to be read later (or never) - Tsundoku.
A browse at someone's bookshelf can give you an indication of who they are as a person, and what subjects the take an interest in.
Books are a great way to enjoy design, both in terms of the colour and the layouts inside, but also the actual design and craft behind the physical book –
http://thebookdesignblog.com/book-design-inspiration/collectors-edition-artist-cover-bomb
It's also a good way to try different approaches to something that we think we know inside out –
http://thebookdesignblog.com/magazine-design-inspiration/lab-periodical
If you can track down the '
Paperback Writer' episode of the BBC series 'The Beauty of Books', there's a talking head section with a gent who compares the experience of reading a book with reading on a Kindle or iPad. I used to have it uploaded to YouTube but it was removed.