The thing is that estrogen/testosterone regulate a lot of different subsystems. Avoiding "side effects" may not be even possible using the technique of manipulating sex hormones. There are two potentially huge markets here, birth control and bodybuilding. The bodybuilders would, if they could, abandon conventional steroids altogether and go for HGH because they've realized that the side effects are just inevitable. A side-effect free Pill is going to need some science which isn't available yet.