I've always found this debate an interesting one, and though I'll make an injection into the subject, know that my basic opinion is that piracy is wrong.
Now, if I go to a store and take a CD off the shelf, that's theft in the fact that I'm removing material that was previously owned by someone else. However, piracy is not the removal of any material object, and in fact nothing is technically lost on the side of the developer. Hear me out here.
If I were to have the ability to get the material and assemble it, I could make a computer that looks exactly like a Dell. Also, I could distribute it as long as it is free, with the only likely lawsuit against me being that I might be tarnishing Dell's name. No one in their right mind would call this theft, as nothing is taken from Dell. Now, the only argument I see is that music/games are theft due to one stealing intellectual property.
However, again, if I were to play music on my own instruments, and again only distribute this recreated music for free, it's unlikely that anyone would call this theft, regardless of how close it comes to the original. This is instead exclusively copying.
Since copying by nature is not theft, I don't see how piracy can (by technicality) be theft. Piracy is only the recreation of existing materials, not the removal of existing materials.
However, one could state that this may be against the original owners will, but I don't believe that the original owner has any say once they have sold their work. I'm allowed to do with my car what I please, and that is more than what's afforded with current laws forbidding the removal of DRM from bought software. So as is, it makes sense that the consumer fights back when their rights are hurt.
Now, to reiterate, I am not pro-piracy, I'm just putting forth some of my musings on the subject.