> I believe from all I have read about Picasso > None of the artists I buy are producing art just for the money and copyright plays no role

You seem to be presuming to know the motivations of every artist to have existed based on your personal experience. Is it so inconceivable to you that there may be someone who, let's say, is considering writing a book, wouldn't at all be motivated by how much money he could earn in return for the investment of his time? And take into account the fact that he could potentially sell the rights for considerably more, the longer copyright guarantees exclusive rights to the owner?