What we do know that Kennedy and Abrams started from Lucas’s treatment and the put them through the normal story development process to take a rough idea and expand it to a workable movie trilogy.
They just had to invent a primary villain in the 3rd movie, as well as contriving a connection between the main character and said villain, and give the other antagonist an abrupt redemption arc after giving every indication that it would not happen.
I’d hate to see what would happen if they didn’t do any story development.