A controversial subject, with two very different reasonings.
*The readers who download our books are likely not to be the people who'd read our books anyway - does this make it right!??
*The people downloading our books for free are putting the readers up in arms who are legitimately buying them, giving them the reasoning of why should I be paying for this when all these people aren't? And yes, creating even more pirates.
There's a great post by Ellora's Cave author, Tracey Cooper-Posey who gives a very valid argument about this sensitive subject.