I do feel bad for the actors because for the most part they're given scripts and have to adapt to the material. Some actors make suggestions that incite small changes but the way I understand it the writers and producers always have the final say when it comes to storyline elements.
And why do I get the sense that Martin only gave the writers the most basic outline of plot points and now is laughing his ass off. He's going to make a killing on the next book because of negative opinions on the last season.