Is this a discussion on art per se or is it really a discussion on property rights.
One of the reasons intellectual property rights disputes are so prevalent now is because corporations producing movie, music and computer programs have entered into the mix.
And corporations have the resources to sue and love to do so because so much money is at stake.
This doesn't really have a lot to do with traditionally what was called art, although obviously derivative/additive art these days have created issues.
I guess somebody has to arbitrate this stuff so the courts is where it ends up.