Actually, the one thing that has never made sense to me is the fact that races for fillies are always shorter than the ones for males. Why not have the Kentucky Oaks be 10 furlongs like the Derby?
It's only in this country that there seems be be such a huge divide in genders when it comes to racing. Not that the horses care of course.
If we're going to worry about gender inequality, I'd think that looking into why there still aren't very many promiment female jockeys and trainers might be a better place to start.