If you look at the OOT, not the saga, but just the 4-6 movies before the changes, I still think Lucas made a pretty compelling story that has a begining and an end. Now in saying this, I will not defend George on changing things as he goes in each movie, but the ironic things is that the OOT works better then the supposed planned PT in it storytelling. Atleast the OOT stays consistent with introduction of characters: You have Jabba & The Emperor mention in SW, and then they appear finally appear in flesh in ROTJ, plus the Emperor is shown in a hologram in ESB. The PT you have these characters pop in out of nowhere. Where was General Grevious in TPM & AOTC? Where was Count Dooku in TPM? It is bad storytelling to have a new sith in AOTC who was once a jedi not even be on the council or even mentioned in the previous movie! You have C3PO & R2D2 with nothing to do in the PT other then they were popular in the OT, as atleast in the OT they were always doing something relevant to the plot to help the rebels. And for Jar Jar Binks, and as bad a character he is, to be dominant in one movie, and then be MIA for the next two movies tells me Lucas was just sticking his finger in the wind.

For whatever anyone thinks of ROTJ, I give Lucas credit for crafting a non-typical story ending with Vader. Lucas could have easily played the 'revenge' card that pervades so many movies, but if you watch ROTJ again, can you name a movie that the protagonist and antagonist meet face to face and don't have a fight, and just talk? Your typical movie would be Luke kill Vader and then finally kill The Emperor with the help of Han/Leia at the end, and everyone lives happily ever after. Lucas I believe tried to make a different story then your usual one in terms of how ROTJ plays out, and sure he may have miscalculated with Leia and Luke as siblings, but overall I always felt the story of the OOT as a trilogy worked real well.