One issue with the free market arguments and the maximizing profits arguments is that we don't live in a free market. Books are a clear example of this.

Publishers sell books, not words. If it was a simple matter of selling words, we wouldn't be interested in top-seller lists. We would be looking at reviews instead. If a book received a good review from a reviewer we trusted (i.e. one that reflected our tastes) we would simply buy the most compelling book that we were willing to pay for.

But it only works that way for people who love reading for personal reasons. As soon as someone wants to read for social reasons you are stuck reading a particular book from a particular publisher. Publishers want to take advantage maximizing their profits, so they introduce a form of scarcity: they limit what they publish to high priced formats.