Originally Posted by
Winter
Maybe it doesn't excuse the lack of screen time, but it might explain.
Honestly, more characters in CoM would have been ridiculous. I can't imagine trying to cram more Organization characters in. And while they obviously didn't do the best job with KH2's story, it was only the 3rd game in the series, on the second where interaction with the worlds really mattered, it takes time to work out kinks. I think the games that have followed since have done a pretty good job of not repeating that mistake, but I could be wrong...I haven't played KH2 in years, and try to avoid fighting the rest of the family to play the household consoles, so I haven't gotten the PS3 remakes.
At the time, they'd also had some minor details of BBS in place as well, I think--wasn't 2's secret ending essentially a trailer for BBS? But while they may have established that he had contact with keyblade wielders in the past, they may not have established how much he had, or what kind of contact he'd had with them. It was barely hinted at again in Days with Roxas and Xigbar, but again, we have no idea just how far they had gotten with that background at that point in time. Just because you have base details fleshed out, doesn't mean you always have full details fleshed out...or Nomura could just like being that secretive--look at how long it took him to explain stuff from the beginning of the series, I mean what number in the series is 3D? Like 6 or 7? And it was only then that he got around to explaining certain stuff from KH1.
I think they did firmly establish what everyone was going to be like--their personalities were pretty clear from the start. They just waitied to pile on the final boss fights until the end, but that just seems to be an annoying KH tradition. XD
EDIT: And while they could have added more scenes to 2.5, Square isn't exactly known for making the best decisions, now are they?