So this is like, really weird, because I'm sure I'm just digging a 13 years old nitpick, but it only hit me now:
Riku gets blasted by an explosion and that rids him of Ansem's shadow.
Yeah, I know. Oldest point to bring up in the book, and I'm sure everyone has exhausted whatever insight can be given on the subject, but I'm just reflecting on how that was a bit hasty and kind of a shallow conclusion to the redemption arc Riku has been on since KH1 (which was also great in CoM).
It could've been a way to keep writing a unique scenario far different from Sora's for him as a character, instead of making him repeat "Darkness might still have a hold on me" for 3 games straight.
It's also proof the non-descript "magic of the heart" fix-it-all was around for a long time in the series.
Now I say that, but I'm not sure keeping a character looking like another character would've been a good move for this franchise, and surely enough Riku's popularity and fandom would've taken a colossal hit.