I think retrospective commentaries are more honest. You don't have to worry about whether it will effect the success of the movie, or how people view it, or if people will hire you, or if it will strain relations with this person or that. People can say how they really feel, unencumbered by politics that exist at the heat of the moment. Its great when Carrie Fisher boos the ROTJ romance and says "give me a break, it was better when they were fighting." She would have never been able to say such a thing if it was 1983. Personally, I find the OT commentaries very entertaining--though I agree: Why the fuck does Ben Burtt hog up so much space?? Argh. Personally, I always felt that Lucas should have had his own, and then everyone else on another, though it seems like Ben Burtt needs his own track too!