This has been discussed to death already, I'm sure, but...while I totally get the critique of "it's a little frustrating how Kingdom Hearts as a series doesn't always plan things out in advance and just retroactively adds new context + importance to stuff later", nonetheless I can't help but think: and yet that's precisely how we've gotten some of the sickest shit in this series. Such as: the Luxu twist which had a cascading recontextualizing effect on basically every single Xigbar cutscene from the last 20 years. Or what about the lesser Nobody from Marluxia's CoM boss fight, which I assume was originally conceived as just a Rule of Cool creature design fit for a dramatic final boss fight, but is now a haunting reference to Marluxia's dead sister? THE GUARDIAN BEING TERRA???

I'll accept some flying by the seat of your pants writing if it means the story and characters are open to being molded into something even cooler and even more compelling later down the line. Like sometimes good ideas just don't come to writers until it's "too late", but if the idea is worthwhile enough and can be folded into the story later in a way that still feels satisfying, almost as if it was planned all along, then why not go for it? Why be held back by the notion that an idea needs to exist from the very beginning to be valid? That's just not how writing works usually (i.e., writers rarely have everything decided from square one, and the act of writing is an ever-changing, ever-evolving process all the way through) and frankly if the story is better for it (IMO) I don't really care all that much just how far back a plot point was or was not planned. Just put in the necessary effort to make it make sense and I'll be happy.

Like I don't want to imagine a world where Nomura got the Xigbar = Luxu idea and then just shook his head and went "No, I can't do that, since that wasn't my original intention for Xigbar and it's far too late now to turn him into that kind of character." Of course none of this matters I guess if you hate the Luxu twist and every other unplanned plot point + twist in the series, but idk, personally I've liked most of 'em (except maybe one or two which I will not discuss here because that's not the point of this post and it's just personal preference anyhow.)