Maybe the Madonna comparison is to how both of them are usually "reinventing" themselves. If you look at it, Hikki's albums all seem to have a different sound and genre to the one before. I dunno, but that's what I think.

She's still the same person, but I would welcome some people comparing her with other successful acts like Mariah and Madonna for people to know who she is and become her fans. Then Utada can show them who she is musically and in person.