Do you buy into every single stereotype? Metal is not macho in my opinion. You're looking at its basic theme extremely one-dimensionally. To me, it's about finding power within yourself and expressing it through aggressive music. Women can do that just as well as men, and to call it either macho or feminine isn't doing it justice. I get the impression that when you think of metal, you just picture Manowar. Sure some bands take it in that direction, but it's foolish to think that it's exclusively for men, or that male listeners are only interested in fucking women and killing things.
Like I said, you have to take a lot of it with a grain of salt and realize that while bands like to explore certain themes, they don't necessarily subscribe to them and live their lives according them. Slayer caught a lot of shit for "Angel of Death", a song about a nazi war criminal who conducted horrible experiments on children in concentration camps. But just because they wrote a song detailing his crimes doesn't mean they condone them. They were just exploring a dark subject through a dark art form. If people don't like it, they don't need to listen to it.