Earlier quoted context omitted.
All the responses seem to be a bit off-target. I'm specifically talking about copyright being linked to the lifespan of the author. It's arbitrary and unfair on authors. I'm not saying we need long copyright terms. I don't know what the optimum would be - maybe 10 years, maybe forever (like indigenous culture).
Our copyright terms need to be reasonable. They aren't reasonable right now. The term has been ratcheted up from the original 14 years with an option for a 14 year renewal to the ridiculous author's live plus 70 years, or 95 years from first publication/120 years from creation (which ever is shorter) for works for hire. I'm all for keeping much of the current copyright regime around, including extending the term to s…
For patents, it's important to ensure that ideas become available for everyone else to enjoy despite giving a monopoly to the inventor. That's because an invention may be the best way to do something and we would be worse off if we couldn't use it. Copyright, on the other hand, doesn't protect anything fundamentally important. It's just individual products of human creativity. If you want a cartoon animal, you can always create your own without having to build on Mickey Mouse. The protected ones don't really matter except that they've been pushed into popular culture and people have lapped them up. We could do our culture in a way that doesn't suck at the teat of industrial culture-generation factories like Disney if we didn't want the impediment of copyright.
So I don't think your argument about give and take is really convincing. We could even have infinite copyright and the world would get along fine. If some obnoxious copyright owner enforced their rights to strongly, somebody else could create an equivalent work that was just as good to replace it.
I don't think they'd do it without copyright though, as evidenced by the fact that almost nobody does. Even open source developers still use copyright to restrict distribution (GPL) and amature artists demand credit (CC-BY).