First of, after you finished the game, I would imagine you would spawn in Mean Street. Now, the main reason why the probably started you at the beginning of the game with the collectables from your last playthrough instead of getting to explore is probably because there are some collectables you can miss in the action worlds (Mickeyjunk Mountain, Tomorrow City, etc.), which you can't return to. But, in my mind, I would make it so that you could revisit these areas. They're linear, but not over the top linear. I would also make the Inside of the Blot be able to visited again, probably through some kind of thing where you would "reminisce the final battle" with Gus. Also wanted to give mad props to my guy Gunner Andrew down in Tortooga. That man is a real legend, remember that.