But.. the fact of the matter is that for music at least, I'm pretty sure that without copyright in the early days, we would never have had the variety and originality we've seen over the past 100 years or so. I remember an anecdote about the Rolling Stones, that they only started writing originals when they realized they could make money off of the publishing. I also notice that lots of early church hymns and political songs were merely new sets of lyrics put on the same melody over and over again. There was no incentive to make new melodies, so people reused. It was a far cry from the diversity we see in music today. People are pretty much forced to make something new all the time.
That said, I love artists like Girl Talk, etc. I just don't know where the right line is.