The different burden women bear from sex (the possibility of pregnancy) is likely one of the public policy concerns in protecting female sexiality more than male sexuality.
So, would there be a distinction regarding oral sex, as no possibility of pregnancy there? In another post here a (female)teacher touched a boys penis 'through his pants'. I don't see any chance of a pregnancy there, so why the suspended sentence? Isn't the issue more (or as much as)what psychological damage is caused to the minor? If your public policy is valid, and with it you seem to focus exclusively on the 'burden of pregnancy' issue, then there should be a distinction when that burden is not a factor.
I understand your viewpoint, (for the most part).I just have a different one.