I think Nintendo prefers to keep its characters low on personality so that everyone will like them. Mario, Samus, Link, none of them speak on a regular basis, and I think it works in the games' favour in some ways because it allows players to project their own personality on the characters.
However, I know where you're coming from. On the opposite side of the coin there are games like Final Fantasy, where most of the characters are quite well-developed, and you come to love them for it. I guess maybe the difference is, it's okay if you have some, or even most, of the characters in an RPG, because you still have all the other ones that you like. If you hated the attitude of Mario or Link, you might not enjoy the games.
As for Wind Waker, from what I've seen Link isn't going to change too much. He may have a bit more body language to express his feelings, but I doubt we'll see very much character development.