I think their argument would be "to cover the inevitable piracy" but I'm with you - the less the charge for tracks the less people would bother to pirate them. If they can get down to somewhere between 15-30p per track they'd make a mint. Why would people download some dodgy bitrate mp3/aac youtube rip off e.g. Soulseek or Gnutella when for stupidly low money they could get a great copy from an official source and not spend half their life looking over their shoulder?
I've always wondered if there was an argument for the police to spot check iPods for tracks. Don't suppose average plod would know what to do with one though?