> From a deontological perspective, perhaps

That actually seems even less defensible than the normal pragmatic, consequentialist position. See Koepsell and Wilson, as summarised in this article: http://www.hxa.name/articles/content/copyright-ethics-agains...

Also, one can see a simple question that no moral argument for copyright/IP seems able to answer: why impose a restriction on a beneficial abundance? (where there is no need and no gain). Copyright creates an entirely artificial restriction. How can there be duty in that, or derivable from that? Why would we want to make a rule to restrict a beneficial abundance? It does not seem possible for that to make much rational sense.