This thread reminds of a post someone here made years ago... I wish I could find it. I'll do my best to paraphrase, "George Lucas hadn't decided on themes or storyline for each prequel in enough time for John Williams to have as much time as he had to create the themes for the OT."
My response was, "wut?" Movies 2 decades in the making (with an "original vision" that dates back to George Lucas' immaculate conception) and George couldn't come up with stuff in time for Williams to write the soundtrack?
WHAT KIND OF CRAZY IS THAT?!?!