http://www.techdirt.com/articles/20090512/0123254841.shtml

Free is sometimes a barrier to adoption. That is, all three often found themselves needing to explain and educate their customers or communities why they were offering things for free, because many people who come from a world of scarcity rather than abundance intrinsically distrust free. They assume there’s a catch or that the service is somehow of lesser quality. This is an interesting point that deserves more exploration — though, a part of me wonders if it’s really generational and will fade over time.”