Hmm, you have a rare opinion there Most, if not every other forum member on this site, really likes to put one on their list, and for all of the reasons you listed here. They think the story is far better that KHII's (which is my opinion as well), they like the gameplay better, they love the platforming and the world-building, and they especially like the art style of the game! It's on the top of my list as well, and, not to offend KHII defenders, but KHII is probably one of the worst games in the franchise. It's sloppy, rushed, and just seems like it was slapped together for the 2006 release date and only after did they decide to fix it and balance it out with the Final Mix.
KH2 may be a bit sloppy, but I'm glad they put their most intense focus on the combat, so it can still be a decent game despite it's flaws. BBS can have it's thematic shit that everyone loves, but it's just a boring game to play. I don't play KH2 much because of it's flaws, but it's fun to crank out critical mode every now and then, because enemies still have well thought out patterns, stagger, and revenge values that make sense.