If you buy a paperback book you're purchasing the physical materials in the book (i.e. the paper and ink), and a license to the copy of the material in the book. You can't do whatever you want with the content - e.g. you can't copy it and sell it on.

It's only now that the materials and the content can be explictly and easily separated that we see this logic actually apply in more meaningful ways. This is going to apply to more and more things in the future (e.g. cars, phones, etc.) so we better get used to it, unfortunately.