"Kids" are going to have sex, we should take every opportunity to provide them with a means to do it as safely as possible.
1. Herpes. It's usually on the level of "slightly annoying" rather than catastrophic. Pretty much the biggest downside of having herpes is the obligation to tell sexual partners that you have herpes.
2. Things that die to antibiotics. Syphilis, Chlamydia, etc. You get them, you get sick, you get treatment, you get better.
3. HIV/AIDS. Treatment is much better than it used to be for this, but it's definitely still the scariest one.
Basically, getting tested regularly is probably enough precaution. You'd feel more regret over picking up an STD than putting too much effort into avoiding STDs, so it makes sense that people over-invest in this area (see also: hiring decisions).
Maybe I'm reading your comment entirely wrong, but this sounds ridiculous? What even is regular testing anyway? I should suddenly be just fine going on tinder or taking men from bars home and not require any condoms, instead just check myself every month and take a bunch of medication if things did go wrong? Or do you mean me and my partner can have sex in our monogamous relationship without condom but instead a regular checkup?
I see the first idea as a terrible idea, and the second as - while safe - a little excessive after the initial checkup when you both are ready for it.