By the same token boys should be allowed to play volleyball and field hockey, yet they aren’t’...
Again, not my area of expertise (and I haven't looked at it closely since my own kids left high-school several years ago), but there have been some challenges to these kinds of rules. None have been successful, but none have really been heard on the merits of the case. Most have been dismissed because they didn't fit some of the criteria of Title IX - mainly that the organizations in question didn't receive federal funds or weren't an arm or extension of the state.
It's my opinion that if a case - with the right plaintiff and the right circumstances - should ever reach the Supreme Court, some of these classic "all-girl" sports" may have to be redefined to include boys - just like football was redefined.