It must be intimidating, as the Avatar, to see all of your past selves incarnated in stone, and worse, be able to consult with any of them as you want. Aang is essentially seeing what he will become, as well as the role he will be reduced to once the next Avatar takes over. He's twelve, so he's a bit cushioned from the full impact of it, but at some point in his life, Aang is going to come to terms with that idea. Most of us find morality scary. I wonder what Aang thinks of it as time goes by.