Interesting article. My own take on this is that if an author signs rights away, he or she can complain all they like about the finished product, but ultimately it is the audience who will embrace or reject the adaptation. In some cases (Mary Poppins and The Shining for instance) the films are unique and brilliant in their own right, even though they deviate from source material. In such cases, I think as long as filmmakers replace what they change with something just as good or even better, the audience doesn't mind the differences. Here are my thoughts in more detail.