I have to say this was one of the things I loved about Black & White, cos they really made the character development well-treated. Especially in the case of N, Bianca and Cheren.
I agree with Batel on the topic of Bianca's father trying to take her home from Nimbasa City. There was no way someone around Bianca's age would be out on a journey by themselves whether they had Pokemon or not.
Like what Kotowari said, I think Game Freak should bring more depth into the characters' personalities but I loved the added realism that B/W brought us.