I get what you are saying and I agree with you, but convenience overrides that. At night, my wife goes to sleep an hour or so before me, so I read. If I had a real book, I would need a pain in the ass book light. With my phone/ebook reader, it is build in.
Also, it is always with me. I don't have to carry it around. Hell, I can, and do, carry around a whole series of books on my phone so when I'm done with one, I can simply move onto the next one.
I still have a decent library of books, I simply don't read them anymore.