If ESB is the same quality as ROTJ, then I am not an OOT fan, cause it wouldn't be worth it to watch 3 movies as part of a story where I am only really love one of the movies. But what ESB does is it makes ROTJ worth it to watch cause it extends the story, and for whatever ways Lucas rewrote the SW trilogy from 77-83, overall it does work really well, and is very enjoyable 3 part saga.
The problem with the PT, is that the quality is all over the place, and that is why so many fans have just put their hands up. Most fans have a huge problem with TPM or AOTC, or both. Many fans like ROTS, but because the two leadup movies are duds, they have a problem cause they can't wait til they get to Episode III, and still have to watch 2 movies to get to the real story. Many fans like me like ROTS, but think it could have been SO much better, cause Lucas really dropped the ball on key points in the movie, and as Brando said in On The Waterfront, "It could have been a contender!"
So what happens now is that you have this mess of PT movies that tie in with the OT, and it all becomes hard to figure how to enjoy the saga 1-6? Now when I say 'mess', I honestly don't hate the PT movies like many here, I think they are entertaining, fun summer movies, but stacked up against the OT and now trying to see it as one saga, it is like night and day. And what you have left with is: The great trilogy, and the OK trilogy, and I just don't think I will be revisiting a trilogy of OK movies 20 years from now like I do with the great movies from the OOT. So in the end, it is all about quality, and that is what the problem is, not the fans.