The kindle lets everyone do what my friend K. used to do, with less weight. In fact, they can bring multiple books otherwise only available in hardcover. But the kindle actually lets you do something else that is even more interesting.
If you own multiple devices which can read kindle e-books, and you leave one wherever you sit and drink your coffee, and wherever you work, and wherever you read before going to bed, you don't actually have to ever carry a book (or kindle e-reader) anywhere. There can be one just sitting there, waiting for you. Conveniently remembering your place in the half dozen or more books you are in the middle of.
You can't do _that_ with a paper book.