I don't think being illegal is relevant, its hardly ever enforced and I would say most teenagers at present don't take that seriously. My teens and I both have agreed when having sex, the law is the last thing on your mind, only once you are 16 and your partner is younger is it possibly a worry.
Teaching children this form of sex ed will teach them from a young age about emotional maturity when it comes to sex, not feeling pressured and so perhaps in the future the law will be more relevant as our children will understand why its illegal to have sex before 16.
They will be more aware that sex is for those who are ready and that often isn't until around 16.
Personally I'm not too worried about teen sex in general, I think its a normal exploration and something I mostly enjoyed. I am worried about STIs, unplanned teen pregnancy and why is some teen pregnancy planned. Unplanned teen pregnancy and STIs can take an understandable exploration down a life-changing path and planned teen pregnancy is often a result of them being misguided. Many look for love through sex, they feel the need to be loved, when they unsurprisingly don't feel loved as a result of sex they want a baby. Educating our children about relationships and sex will dispel these myths and mean they are better prepared when the time comes.
Teaching them this at 13 & 14 is often too late for some. Also I still maintain this isn't that shocking, the only part I don't like is an orgasm being described as a tickle. I don't want a game of me tickling her being talked about as "mummy gave me an orgasm"!