Newsflash - men don't usually have muscles like that either. They have to work hard to get them, so why shouldn't a woman, if she so chooses, do the same? Would it be OK for her if she were a superhero or Xena, warrior princess? If so, why is not OK for a woman who they've pigeonholed into a "pretty actress" role? What these dudes don't seem to understand is that while it's fine to have preferences, it is not fine to assume that every women is dying to contort herself into fitting into yours.
As I understand it, Kidman is one of those people who is just naturally very thin. I remember hearing about Tom Cruise baking her cookies to try to keep some weight on her when they were married. Deciding that she's been "over dieting" when we don't actually know that this is the case is yet another way that these men think they have the right to police women's bodies.
Good article!