The creators put in labour with the intention that their efforts would be recouped in the form of remuneration. You stole their labour simply because you could in do it in a way that is not easily visible/detectable. Theft of labour is still theft to me, be it Amazon or parasites on creative works that are the results of the cumulations of years of an individuals learning and mental effort to create something. There is a reason copyright was created. We wanted a mechanism where these people could be rewarded for their labour because having professional fiction writers/historians/philosophers benefits society.