The big question, though, is that unless you clarify it, the artists themselves don't know exactly what you mean. They could be in violation of this clause by producing an original and then selling 100 prints or whatever. You know, artists sometimes do an original and then do 100 copies of it.
I think there needs to be some clarification so that people don't unwittingly infringe on this clause by doing something that isn't a large-scale printing and distribution of postcards, etc. I'm in agreement with the intent; I just think there needs to be some clarification so we don't have people unwittingly getting into trouble.