I didn't really feel like they were fleshing anybody out in those missions, except to show us how those members behaved around Roxas.
That's already fleshing them out more than Roxas and KH2 Sora got at times. Especially when you keep in mind that despite not everyone reading them, there ARE Secret Reports written by Demyx and Luxord. Luxord's reports in particular I found to be fascinating and enjoying seeing his critical way of thinking and analysing things, even he himself.
but that everything about their so-called "fleshed out personalities" were traits I could've figured out myself in KH2.
I disagree. And I dare say those characters went through some differences in light of what happened in Days. I mean, for someone who showed at times concern for Roxas and Xion, for Demyx to be
happy about offing "the traitor"? And no, there's very little in Luxord's Secret Reports that KH2 implied towards. There's quite a bit of depth to that one I can appreciate in Days that KH2 never tried bothering with.
Nomura basically confirmed what I'd already guessed about them.
And that, sweetie, is what makes you not that fazed by their insight in Days while not all of us saw it the same way. Also, there's a difference between guessing based on a minimal amount of appearances and screen time compared with numerous missions and reports whose intentions are to show us what KH2 left us
guessing at, being what the Org truly are like, without leaving any room for doubt or too much debate.
Arguably, in KH2 you could've seen Demyx as a pacifist; Days proves him to be a lazy coward. Luxord seems to be, yes, a lulzy pimp; Days shows us he's one of the most intelligent, calculating characters in the series; he just doesn't have too many alterior motives to have enough plot relevance, but I can hardly say it was anything KH2 even tried hinting towards.
Sure, it was interesting to see how they interacted with their fellow members and to get that confirmation on their personalities, but I still think they could have done better with that.
I agree and disagree. Sure, they could've shown more, but even in a character-oriented and driven game like Days, there's so much you can expand on the non-relevant characters. That's more for the novels, and people keep saying the novels do what the games don't - well, shocks, because the games don't try to do that if they ever even could, seeing their basic plot orientation.
And that's where I disagree because Days still went out of its way to elaborate the characters and their personalities and I dare say their growth. Even Luxord and Demyx gradually opened up to Roxas.
For better or worse, however, Xion was the plot device that half the Organization were plotting to use for their own gain. That leaves little for Luxord and Demyx to do, lacking any visible ties to BBS, and even for Xaldin who even in BBS seemed to play quite the minor role (apprentices do guard work now?).
And look at what they did do with the yes plot relevant characters. Axel and Saix? You said yourself Axel was introduced in a satisfying manner, and with Saix getting bonus screen time with Xemnas and Xigbar, he's alright too. Xigbar intrigued us plentifully with his treatment of Roxas and Xion and then seeing Ven in Xion, leaving the only one to truly be unsatisfying to be Xemnas, but seeing the overall attention the Xehanort faction's getting as well as his own share of BBS references, I can't be too mad at him either.
Anything else is fanservice that not only belongs in the novels, but literally has no place in the games seeing the characters' relatively secondary roles.