There is another reason people expect stuff to be free and it's because business people in general don't know of any other way of framing things. The last 50 years has been all about advertising and so the business culture knows how to tie ads with content but they don't know how to create great content and convince users to pay for it.
Flip to the last few pages of any technical book. I know for a fact that O'Reilly books put a plug for other related O'Reilly books in the last few pages and I'm certain most other books to the same thing and some even have them up front. Technical books I think qualify as good content.
