I was just thinking about this exact thing yesterday. At the press junket for the '04 dvd, Kershner said "I don't know what he's talking about" in response to some guy asking what he thought about the SE. Kershner just said that the color was enhanced, the sound was enhanced, they added the snow monster and that was it, "it's the movie I made." Maybe it's just because special effects are special effects and he himself said that wasn't his department or forte. He's a humble director who realizes that there are other people involved in making the movie besides him, something Lucas doesn't have the biggest respect for.

Kershner obviously had Lucas's blessing to do the SE of Empire, but I don't think ROTJ's would have been as bad if Marquand had still been alive in '97.