5. Darth Vader Should Have Hunted Some Jedi
This one one would be a little tricky, but we never really get to see Darth Vader at his prime in the prequel trilogy except for the attack on the Jedi Temple, which we don't really see much of on screen. It would have been nice to show him hunting down some of the Jedi that escaped Order 66 either before or after he has to wear the suit. It wouldn't have really needed to be anything more than a montage to be effective, but it would have helped establish that he's become the villain that he is at the beginning of Episode IV and get to show one of the all time greatest villains do something we never really get to saw him do.