I finally came up with a theory for myself, and maybe others feel this way: ESB is a classic, and no Star Wars movie ever reached those heights again. For 25 years now, I have been deluded myself into thinking that SW, the saga, is greater than it is. That is the reason I still latch on to the prequels, watching them every once in a while, just to see if I am missing something, I am hoping maybe this time I will love these films.
When SW came out in 1977, I loved it, and to this day it is my favorite film of all-time, love the characters, the story, Vader, the effects, the music. Then ESB came along, and did the unthinkable for a sequel, it one-upped everything about the original. The characters were more interesting, the story got more involved making it a much bigger universe, Darth Vader was even cooler in this one, the effects were much better, and the music was even better too.
Since ESB, I have been naive about the saga, the other movies have their moments, but just aren't great movies. Now ROTJ gets a pass from many from the OT generation, because it completes the trilogy, gives us closure from the first two movies, still has the lovable characters: Han, Luke, and Leia, and if you put them in any movie I will root for them, and finally it did one scene right: Vader/Emperor/Luke finale, that was the key to the whole trilogy, and Lucas & Co. nailed that scene to perfection.
But is ROTJ a great movie? No way. Is it a good SW movie, yes. That is the problem with the post-ESB movies is they all have their moments of SW fun and enjoyment, but they also have their negatives which cant be ignored:
ROTJ: Great finale, but those damn ewoks and the jabba scene goes on too long
TPM: Darth Maul ignited his double blade was cool as hell, but Jar Jar, Jar Jar, and an 8 year old Anakin?
AOTC: The Clone Wars and the last half hour of the movie move at a frantic pace, but the love story, UGGH!
ROTS: We finally get to see the duel, and Yoda vs. Sidious, but the 'turn scene' and Padme losing the will to live?
My point is that out of 6 SW movies, there are only 2 great ones to me. That is 33%! Now as I said, if it was just Episode IV,V,VI, then 66% would be great with a good ending, and since 1983 I have never had a problem with that. But 3 more movies that aren't great, I just don't see it as the great saga anymore.
If ESB would have been a good/or pretty good sequel, I think most older fans like myself wouldn't be fans of the saga. We would love the original, and like the sequels (or how many there were made after that) and be content. But when ESB was equal to the Star Wars, all of the sudden you think, why can't every movie after that be a classic? And through the prequels I have constantly built them up that way, this is the next ESB. But that never happened.
In the end, if I try to see it 1-6, it is too hard for me, cause that is when I see 2 great movies, and four average movies, and it just doesn't fit for me. If I see it as 4-6, as I had since 1983, I don't question as much, because the originals left all those questions unanswered. In hindsight, as I look at it now, I kinda liked those questions left up to the imagination.