I recommend reading "The Pirate's Dilemma" which is available from $0.00 upwards at http://thepiratesdilemma.com/download-the-book
Edit: The difference between the high fashion brand and the low price retailer clothes are quality, perceived quality, recognition/brand, legitimacy and cost. Which is more or less the same difference as between a pirated copy and an original one.
I do get your point though. fashion and files are not the exact same thing, but are more related than one thinks. There's also other effects of the consumer being the distributor. Even 10 years ago there where no scalable method to distribute out-of-copyright works in a non-profit way, and therefor a lifetime of copyright made more sense.
(1) Hopefully has the same meaning in English, what I mean is that it's constructed and not a prerequisite for the act of creating things. Copyright law is cultural, not 'natural', as demonstrated by the pressure of US companies and government on other nations regarding copyright law.
Let's not assume this either. Maybe this would result in more people who actually want to create, rather than doing it for the money, entering the industry. It would also avoid the middlemen who just skim off the top and don't add a lot of value.