Why teach Women only class's?
IMO based on my own experience, and training.
Women are in a unique position to be totally in a victim class. While many women are totally capable of defending themself (my daughter for example can kick the average man's butt, and she carries a shiney .38 with pink grips for those she cant), they are almost always percieved as a potential victim. Women tend to be smaller, weaker in upper body strength, and women walk around their entire life with the ultimate prize.
Some people have developed stratigies, and technique uniquely female. One thing I learned in life is that women are victims far more often than ever reported. Women are victims in more ways than most people could ever imagine. In my experience 99% of the time when a woman is a victim the perpetrator is a man. IMO Women need and deserve their own skillset to protect themselves. IMO The most effective tactical advantage in a self defense situation is surprise. A woman who has a skillset unique to women will have that tactical advantage.
Again based on my own training and experience.