Reminds of football coach in High School. He was 24 years old, had played 2 or 3 years as a safety in the USFL, and every single girl in the school was madly in lust over him. Would it been OK for him to sleep with the girls, "because they wanted it", of course not. Would it have harmed the girls, probably not, it would not have been the first sexual experience for most of them. You have to set rules for all teachers, otherwise what happens when a Homo gets into some poor confused 13 year old? Well the kid enjoyed it, etc. you let the hot chick off, you're discriminating.
I still think there's a slight difference between a female adult/male teen and the reverse. I'm not saying it isn't bad/wrong, or that it shouldn't still be illegal, just that there's a difference. No, I don't think that because I have fantasies about former teachers. I don't think I ever had such fantasies.
However, I don't blame anyone that insists there is no difference. I wish everyone would behave that way.