If the truth was to be let out illegal file sharing would be much less if the books were readily available in the formats that the most people could buy and read. Most illegal sharing is done because there are the ones that can break the DRM for the ones that can not read the books because of the restrictions other wise.
It is a fact the more you restrict something the more you encourage illegal use of it. That has been a fact every since creation.
Just my two cents
Chuck