I hate people negarepping for disagreeing. I'd be soooooo far into the red had that been the norm XD
Actually, both Roxas and Namine are exceptions, but the fact is that that's what lets them age. Also, their Hearts not being covered in Darkness and thus their Senses of Self can be "updated" (Roxas would get new Memories from Sora as he grows older even on a physical-Memory level, and thus would grow older too) so that can explain it as well.
And I negad him. Really. EVERYONE tells him he's wrong and he comes after me.
So back to ignoring him~
Uh, but she did. Even if it's them being lazy asses and using the same Vectors for both Sora-Roxas and Kairi-Naminé, the fact remains that Roxas in KH2 is not KH1 Sora's physical size. And Naminé in KH2 is not the Naminé from Re:CoM. They both grew older, and if they did it because they were lazy, they must bear the consequences it has on the plot.