Honestly, I don't think I've seen where it's said a big theme of the game are those two things. I've seen the Mark of Mastery, the Data inside Sora, and trust be the themes, but not those.Why would it be important? A big theme of the game is "the hearts within Sora" and "the hearts within Xehanort." It's one of the wham lines of the trailer. Considering that Roxas and Xion inhabit Sora's heart, and considering that we've seen Vanitas, I don't think I'm being unreasonable.
Vanitas, right now, is most likely to be in Xehanort's heart, if Grass is correct(Which he mostly is with his theories).
Yeah, and? Excitement and urgency can be available in those battles where you need to swap out and regain health.Well, I'm sorry, but I have to disagree. Quoting Nomura here "Regarding character changes, he said that it will be easiest to understand if you think that there's something like a countdown event always taking place." Tetsuya Nomura Discusses Kingdom Hearts 3DS -- Andriasang.com
A countdown adds an element of excitement and urgency to gameplay. Now don't misunderstand me, I'm not saying that chaotic gameplay is a BAD thing, in fact I think it'll be quite good. But please, don't try and say that the drop gauge won't be chaotic, because it will.
And how do you know the Drop Gauge will be chaotic anyway? We've not seen how it actually works, and from the descriptions we've gotten it seems like it's not chaotic.