I loved the alternate scene/deviating thing… even if on my first play through I had no idea it was happening.
On my first play through, I am pretty sure I did Olympus and Deep Jungle before Wonderland, because I remember Snow White being the princess who the Disney Villains capture at the end of Deep Jungle. Otherwise I did the game in standard order. When I was young, Kingdom Hearts was like nothing I'd ever played before, and it was the first game I was actually afraid of, and I grew to really fear for the universe, especially when favorites of mine like Simba had their worlds destroyed. So it never crossed my mind to leave a world once I started it because I was that determined to save the worlds - besides going back to Traverse Town to restock my supplies, that is.
Regarding this alternate take on Monstro, it feels like completing Hollow Bastion before it renders Monstro pretty much non-canon since as said, there's no point for Ansem to be dicking around inside a whale's innards. The fact that you can abandon Monstro since it lacks a Keyhole is something that was initially off-putting to me, since you had to struggle to find your way around that damn maze all for nothing. But, then it turns out that it's only in Gepetto's house that you can get a torn page. And I certainly wasn't going to allow Pooh and his friends to go without being reunited.