Why do people think "hardness" and "toughness" are so important?

Well, I heard a review of a women's magazine survey a few years back that reported the number one attraction of a man to a woman was something to the extent of 'his dangerousness'. Go figure. It's best to not clear up this question about you with a lady, just as it is never to harm or threaten her. So what is it that fills her needed perception of this? Oh to be swallowed by a whale and show'er.