Re the why are we teaching it - don't you think it's all part of the necessary message of Taking Sex Seriously? Which shades into all those things like Don't Be Naive; and Be Aware that He May Feel Differently Than You Do; and When You Say No You Are Entitled to Mean No? All of which we were so not taught, back when?
When I was at college we were given something called The Little Blue Book, which covered all the above, and was an essential for me. Especially since I found out, to grisly cost, that I was prone to cystitis - and that, accordingly, it was a fairly good idea to be a bit careful & it wasn't all going to be flinging the birds & bees to the wind. All of which I think people should have an idea of.