The reason why some artists look 'cutesy' is because in Japan, cuteness is attractive to them.
That's part of the reason why Ai Otsuka 'sounds' 5
Well, we're talking about images here, not voices..
I see Mika doing rock for NANA2.. I agree with one person that her voice is more suited for ballads. I LOVED Glamorous Sky, but the rock genre isn't really for her. There are just certain people that can pull it off.