Is making movies inspired from books a good thing to do?

The people making a film must apply for permission from the book author/publisher in order to be given what is called "the rights" to the film. If they didn't ask, they would be sued. Some marvellous films have been made from books but there ahve also been dreadful examples where they should not have bothered. "The Shipping News" and "The Cider House Rules" are quite recent examples of brilliant movies adapted from books.