There's almost no resemblance between Sora and Ventus. Roxas's appearance obviously comes from Ventus, even though Sora is supposed to give some resemblance. Your theory doesn't make sense. Their appearance in the KH Universe just sounds stupid. Sora looks just like Ventus/Roxas looks just like Sora in game, but to us they're completely different? I doubt that Nomura wants us to think that.
Then why would they go out of their way to put a statement in game saying that Roxas and Sora look just alike?
That was their intention from the very beginning. Don't try to say it's not true because YOU can't understand.
It's possible that Sora got his looks from Ven, and pretty plausible, too. We've already seen cases where certain people influence the appearance of others, one of those cases being MX and Braig.
I really disagree. In this case it could easily be applied to both.
Except that Aqua was only on that world maybe 5 minutes before they met. She was literally speaking about his physical attributes. Both do not apply in this case. Just the one.