Lucas screwed it up with irresponsible directing. I can imagine Hayden and Natalie doing great takes, doing the best they could with the dialogue, and then Lucas having them do it over again. Remember, Empire Strikes Back is his least favorite Star Wars film. Meaning he has jealousy problems, or, I think also he has crap taste in what's good in film.

Lucas is an idea machine. He has some good ideas, but he faulters as a writer and director to the point that I'd consider him downright incompetent in those areas. Realize how important they are in making a film a classic.