That needs to change. The only way that will happen is to change the message from "its ok little snowflake", to "No, that is f*cking dumb, and you shouldn't be doing it."
... man, I hear what you're saying, but the cursory student of history in me notes that they've been trying to push that message on kids, sometimes with literal and systematic physical abuse, for centuries... hell, probably millennium. And failing.
Every time sex avoidance has become a major aspect of a social group, large or small, it's neither stuck nor been effective to any particularly meaningful degree. It's, just. It hasn't worked. Pretty much every sign points that it
won't work. There's a relatively limited set of things we're more or less wired to do, and, well...
I'd say do what nenjin said, but don't waste the effort actually trying to influence the social attitude regarding the subject. It doesn't seem to really matter
what the social attitude is. Permissive or impermissive, what's considered underage sex these days happens anyway, and it happens to a pretty great degree. Only thing that social attitude seems to change is the reaction to it, rather than much in the way of frequency. And from what I've seen "special snowflake" seems to do a lot better on that end of things
Note and highlight the risks, sure, but keep stigma as far a way from the subject as possible. Risky and full of serious consequences, but a lot of things are that we don't call fucking dumb.
Again, by that line of reasoning, increasing the sex ed will only make the matter worse.
Only if sex ed consists of saying "No" first and loudest.