They gave a very public example of the problems with locked/controlled content and how it tends to directly oppose the consumer.
When you make a purchase for the Kindle, you're not buying a book, you're buying the right to view the content of the book in a limited context.
Actually, that's what you do when you purchase any copyrighted work. Copyright law prohibits you from doing a wide variety of things with some things you buy - copying and creating derivative works being the big ones.
I am free to do virtually anything with the original including archive for all eternity, loan out relentlessly, sell, or chop into small sections and sell the sections.
I can even copy within certain contexts (archival copies of software, for example) and I can create certain types of derivative works (parodies and certain limited educational uses for instance).
You are not allowed to show to an audience a movie you bought on a dvd. There may be other examples.