Just a brief post script:

“But if you sell a work to somebody, they have the right to do with it whatever they want, don’t they? Include destroy it? ”
Actually no. There’s a law about that concerning visual artworks but it would take too long to find and quote. I had occasion to refer to it years ago when a very large mural I was commissioned to paint in a public place, which took me over a year to work on and which featured portraits of many old people and children who used the center, was completely covered in red paint a few years later by the next administrator of the place.
But I do see your point and generally agree with it. As long as originals are kept intact, I absolutely support interpretations and quotes etc. from artworks of any kind. What I meant was, if all the originals of works by X,Y, and Z had been “altered beyond recognition” by anyone and everyone then we’d never know what those originals were like.