So I just read the threads about second world visits and it got me thinking, what if the concept of worlds in KH4 had you visiting a world periodically. Hear me out: instead of a central focus mission, characters in said world (Pain and Panic, Athena, Hercules) would have missions that would pop up throughout the game as you progress through the main story and you could either focus on main missions, or get more of the overall story for that world by following the side quests? It would be a little harder to follow the movie plot but it could flesh the world out a lot more. It's one thing I'm seeing as a giant roadblock at the rate KH is picking Disney movies.
Example: You just finished a main quest for Leon in Radiant Garden. You get to the gummi ship menu/world map and you get an alert notification. "Hamm is having a battle in Verum Rex 2 with Rex and he wants your help training him! Hermes has lost one of his sandals and doesn't know where he misplaced it! Pongo needs you to find puppies that have left the house and are yet to return!" and a main quest notification "Leon said that the key to finding out where Luxu went can be found where Captain Flynn hid his greatest treasure. Coordinates have been added to the map."
Example: You just finished a main quest for Leon in Radiant Garden. You get to the gummi ship menu/world map and you get an alert notification. "Hamm is having a battle in Verum Rex 2 with Rex and he wants your help training him! Hermes has lost one of his sandals and doesn't know where he misplaced it! Pongo needs you to find puppies that have left the house and are yet to return!" and a main quest notification "Leon said that the key to finding out where Luxu went can be found where Captain Flynn hid his greatest treasure. Coordinates have been added to the map."