I don't know that a pirate's motive is really what determines whether or not piracy does good. I read somewhere at some point [citation needed] that a large percentage of the people who pirate wouldn't otherwise have bought the thing anyway. In those cases, that pirate would maybe never have been a sale, but is still spreading feedback and recommendations for the thing through word of mouth, and then some of the pirate's friends might buy the thing, netting sales that wouldn't otherwise have been made.

Of course whether or not it's ethical is another matter, and that's where motive probably comes in.