"If you think about the focus of this part of the Star Wars saga, it's on survival, not triumph. The theme of Empire is that for some people, for some part of their lives, just surviving is enough of a triumph for that moment. And because of that, because of Luke's feeling that he was ready to challenge Vader and then his realisation that he wasn't, and was also unable to save his friend - all these things are important to the emotional state at the end of the story. This episode, the middle act, has to be slower and more sombre in a way. It spends the time to delineate the characters a little better, it explains some of the motivation and so on. It wouldn't work if you had three films that are exactly the same."
Gary Kurtz, responding to criticisms of the time concerning Empire's downbeat cliffhanger finale, to Starburst magazine Issue 23, 1980.