I think it's worth bringing up a factor mentioned here a while ago - Piracy serves as a useful market signal. The fact that people are pirating content means there's demand - if they're pirating it, but nobody's paying for it, that means the rights holders are creating a product people want, but the price & delivery mechanism aren't right yet. That's an awful lot better information than just that people aren't buying something - and I'd argue it's one of the signals that got the record industry to actually start taking DRM-free music sales seriously.

Obviously it's not a great signal on price - piracy's always going to have the lowest price - but knowing there's demand means you can start to adjust your strategy to try to capture some genuinely lost sales.