Bingowings said:

Protecting art and culture is probably something that you just can't trust to a free market.

Very important point. The "it's his he can do whatever he wants with it" argument presumes that ownership is the be-all-end-all of society. there are many cases where society places restrictions on what you can do with your stuff:

it's my car I can drive it however I want
it's my house I can make it look however I want
it's my kid I'll raise her however I want
it's my historic structure I'll tear it down if I want
it's my money I won't pay taxes if I don't want to
it's my lab I'll make whatever substances I want
it's my life I'll travel wherever I want

Most artists aren't so ridiculous with their own masterpieces as Lucas is, so society hasn't had to deal with this issue yet when it comes to art.