>transformed from these simple ideas into great films (lots of iteration, lots of early prototyping and feedback, etc.)
I don't doubt there's lots of feedback on details, but I have doubts about how much story arcs might change, or how "rough" the originating ideas are, especially after realizing that "Toy Story 3" is just (imho a lessor version of) "The Brave Little Toaster" as fed through the "Pixar Process".
It's toys instead of appliances, an attic instead of a cabin, being repurposed at a daycare instead of a repair shop, and an incinerator instead of a compactor, but the pixar process didn't change the overall story at all.
(The idea was originally Lasseter's, but to oversimplify, he basically lost the rights and others ended up making TBLT, while he eventually got to do TS3.)
Maybe other movies saw more changes going through the process, but the only example we have to actually compare didn't.