I think the point raised about Lucas becoming a dad by ROTJ is entirely valid. Certainly fatherhood has affected his art; he hasn't become "soft", he just thinks about things more. Why else would he consult a child psychiatrist about the revelation about Vader revealing himself as Luke's dad in the previous instalment? By the time of the prequels, Lucas had separated from his wife and gained sole custody of his children. So now, more than ever before, he was aware of his responsibility as a storyteller and the messages his films were sending out to their target audience. Maybe this is why segments of the prequels feel a little laboured whereas the OT had a breezy, devil-may-care attitude to it.
Part of the appeal for me with ROTJ is it has a the-gang's-all-here tone to it. Yes, some of the actors are going through the motions - except Mark Hammill, for whom this is his shining hour - but the sequences between Vader and Luke fail to be diminished by this (and this really is their film, right?) and I really like then sense of this-is-the-last-one-so-let's-go-for-broke (a second Death Star is not so bad an idea - after all, people still make nuclear weapons don't they?).
Watched in the context of the bigger story, the opening of the film is a blessed relief after the darkness of ESB (in the same way, ANH is a breath of fresh air after the death and misery of ROTS) and I'm sure that was deliberate; the characters are really put through the mill in ESB, we really can't see them going through all that again in this, the final episode.
In retrospect, Kersh has made some observations about ROTJ that I do agree with. He said there's no sense of danger for the characters, they never seem in real peril. And how could they, with such appallingly choreographed sequences as the fight over the pit of Carkoon and the fighting on Endor? Also, the film moves from one set piece to the next in quite a ruthless fashion. I can't argue with these criticisms. Kersh also said he'd never have removed Vader's helmet. I think the story demanded that we see Vader's face, though, to drive home the message that the machine side of him was dead, and he had regained his humanity.