It's important to note that different Pirate Parties are endorsing different copyright lengths.
In the UK, it may be 10 years, and Sweden it may be 5 years, but in Australia, we think that 15 years is a safer option with respect to how well-received this kind of reformed will be, with respect to business.
15 years means that Windows 95 would be coming out of copyright, as opposed to Windows XP, which is still heavily used and marketable. If XP were coming out of copyright already, nobody would buy the newest version, because XP is good enough. That might please some, but it will only act to gain us a new enemy at a time when we need to be making friends. In 5 years, XP will still contain a lot from which society can benefit, but without alienating its makers.
We will never manage to achieve serious change if we open too many fronts at the same time in the war against oppressive copyright, and we still have so much to achieve with respect to civil liberties.