I remember a post from a while back (it may have been from the author of SizeUp for Mac) that concluded that customers who paid little or nothing for an app were customer support nightmares. I believe it was attributed to a sense of entitlement on the customer's part.

The author of the following post seems to think they are. At least, they neglect the possibility that many who downloaded their app for free would not have paid for it. https://shiftyjelly.wordpress.com/2011/08/02/amazon-app-store-rotten-to-the-core/

Don't ignore the selection effect. Get your counterfactuals straight. Did the author lose money by giving away to customers that might have paid? Probably. Should he count every download as a loss? Surely not.

Sometimes, people just want a free turkey sandwich. http://www.freakonomics.com/2011/10/03/goodbye-turkey-sandwich/