Stop and think about it. KH2 ended all those years ago with Sora and Riku getting a message in a bottle from Mickey from Kairi.

Then Re:Coded told us what was in that message.

But now, DDD has given us a new bottle, Ansem's Data, hidden within Sora. Provided that this bottle manifests physically when Riku leaves the Sora's Heart... then we have a stable loop, that can have the plot make sense without playing all of the 'unnecessary' games.

Here's how: Sora and Riku have this new bottle with Ansem's data in it. This is hinted to pertain to all of the hearts attached to Sora. It also looks identical to the bottle received at the end of KH2. Sora and Riku can simply act like THIS was the message they got, which details the existence of Xion, and how to save all those other people. Suddenly the plot catches right up.

Now, if Square does this, I doubt they'd make it perfect. I'm sure they'd reference the past games a fair bit, after all, they WANT people to buy their games.

But yeah, thoughts?

Story intense game series like KH aren't something that you can really be casual about. There are plenty of other games casual players can play, in fact most of them. However; KH is one of those games that is inherently BETTER when you know everything that is going on.