I think if anything, giving consumers good, relatively functional games at reasonable prices does more to stop pirateing than other factors. Just look at the music industry. For nearly five years the only way to get music over the internet was p2p networks. No legitimate option existed for people despite a large demand. Now that many reasonable pay p2p networks exist, many of the former piraters are willing to pay for good quality music.
Pirates will always exist, making sure that most customers do not feel it is much better to pirate is the key. Of course it is more complicated than this, but this is my humble opinion.