Ideas and artwork have more dimensions than just the financial value though. They are contributions to culture, which is socially constructed through interaction and the exchange of ideas. I agree that you should have the right to use and profit from your work as you choose, and that it is an asset that you should be able to pass on to your children, however if you manage to create something that is still relevant and useful, 75 years or more after your death, that thing would be foundational to many other things, much as Dracula, the films of Georges Melies or the the plays of William Shakespeare. Why after that amount of time, when they have become reference points and cultural building blocks akin the Bible and folik tales should works not be available in a Project Guttenberg kind of fashion?