If piracy was legal, then anyone who made anything would never be compensated for their work, and if they made their living from it, then they won't be able to do it.
While I have never pirated any content, the only reason I would is if there was some sort of draconian EULA or DRM that only benefits some faceless corporation that see's it's customers as money bags. It still would be illegal, but better than giving in to something I don't support.