As a counter-point, I'd bring up Stephen King's experiment, where he allowed free download of his book and asked for a tiny donation in return. Very few of the people who downloaded the book paid for it and the project was scrapped.

In the final reckoning, King had somewhere in the ballpark of 71% payemnt (i.e. 71% of those who downloaded kicked him a buck, as per agreement), and made something like a $400,000 *profit.* The projected wasn't "scrapped" at all, but rather back-burnered in favor of other projects (which he is contractually obligated to complete.)

Your major point-- that big names hardly need to benefit from the name-building power of distributing freebies-- still stands, but the King facts were wrong.