Emotionally involving the audience is easy. Anybody can do it blindfolded: get a little kitten and have some guy wring its neck.
George LucasI felt that one of the major issues in the third film is that Luke is finally on his own and has to fight Vader and the Emperor by himself. If you get a sense that Yoda or Ben is there to help him or to somehow influence him, it diminishes the power of the scene.
George Lucas