I think I just might have an idea of what Sora's clothes might mean, and I apologise if this theory has already been posted before. If you notice that Sora's new clothes is a combination of mostly white and black with some dashes of red and blue. Now, it occured to me that the red might be for Sora to change to the red drive and the blue for Sora to change to the blue drive. It might be possible that Sora gained his new clothes after he got out of the pod, which might be where Kingdom Hearts 2 begins, and if you still remember that Namine told Sora that he has to go into the darkness of his heart to regain his memories and its not easy just to pick them out without leaving a trace of darkness on him. This might explain the pressence of the black and dark colors on Sora's clothes, but this doesn't mean that Sora is evil. Maybe he is using his slightly dark powers for good, similarly to Riku. Maybe the dark powers in him are inabling him to fuse with Donald and Goofy in order to bring out the Blue and Red drives respectively, since Donald and Goofy were both in the pods like Sora and gained some dark powers while also trying to regain their old memories back. So maybe this is the big secret of Sora's clothes. Your opinions are deeply appreciated...
Kairi...
Kairi...