Originally he had more scripts made, the story line itself was made. It was set. But they were under a lot of time preasure and a rather tight budget that simply did not allow for all episodes to be made. That and the current techhnology gave certain limitations to it as well... That said, Tarryk is right, he chose episodes 4-6 because they were the ones that explained his universe and setting more thouroughly than any of the ohter episodes. Number 6 is not where the story ends either. But seing as the cast are all to old to do it now, the post-empire stories remained novel fiction. It was never as detailed as the expanded universe is now. But luke opening the Jedi academy and Han and Leya's kids playing a role later on was determined back then as well, tho only on paper.
Still tho, I think he should have stopped after the trillogy. The follow ups had no chance of carrying on what the originals had created, and the current "trends" in movie culture ruined it in my oppinion.
The fact that it now had to contain an element of "slap-stick-easy-to-follow" humour was never a part of star Wars. It's the same thing LoTR suffers from but I will not get into that again. Jar-Jar was never an original character. He was added so children and the younger female audience would see the movies. This is not ment as descrimination, but let's face it. Women are not known to like Star Wars. So he added something cute. Which, in every aspect, was nothing short of theatrical necrophelia. Taking a long dead movie story line... And givin it a good bangin up the rear.
The original wit was served cold by Han Solo's sly remarks and C3PO's constant shambles. It was not hard to follow, but it was witty. Not some ridiculous creature who stuck it's tongue in power conductors, was unable to speak english at a post-3. grade lvl, and whose sole purpose of existance was to sell lunch boxes.
I personally never took much pleasure in any of the new movies. I will watch this one all the same, fan boy as I am, but I highly doubt I will enjoy it. As far as I'm concerned, George Lucas should have stopped while the going was good. Instead of attempting to milk it to it's last drop. Doing so has produced these stagnant, sour drops, with which we are forced to satisfy our thirst.
Tm