If they aren't selling it, they they are losing nothing when we pirate it. This in turn means that there is no damage to them, and thus no case against us.
Also, I think very few people would argue that it is immoral to videotape something off the TV and keep it indefinitely (although this is not usually legal, an overwhelming majority of people do it). As I pay no blank-media levy, (unlike in Canada etcetera), and have never completed a ratings survey, it makes no difference to the copyright holders if I record off the TV or download off the internet (I do not have a HDTV, so that argument is moot, and I always fast forward through the ads on videos). Thus, if you accept videotaping of TV content, it is nonsensical to argue that downloading the same content is not acceptable simply because you accessed it differently.
If they are selling it, but there are artificial barriers caused by legal restrictions on over-riding region coding and the like, then this could be argued to be an illegal restriction on free trade under WTO rules, although we all know that no-one with the money to fight such a case ever would.
This doesn't quite ring true, but it is irrelevant to my point above, so I'll ignore it.