I have an odd relationship with books. I like books and enjoy reading, but don't read so much anymore. I don't feel that buying printed books on the whole is necessarily warranted or indeed responsible. At least, not all the books one buys. Owning an iPad has actually changed the way I read, but not the frequency with which I read. I used to read a lot more and it's something I think I would benefit from changing. I have the tools, I just need to form the habit.
Books require a significant investment in space, and repay that investment not only in enjoyment but also in aesthetic and social wealth. You can learn a lot about a person by the books they read and shelves full of books are a beautiful thing in their own right. There are books that I own print and digital copies of purely so that they can be on display because I enjoyed them and want to be able to share that with people. I'm not ashamed, even if that seems contrary to my usually minimalist tendencies.