An excuse I always used to hear for lingerie armor in otherwise serious settings is "It's to distract the enemy"
Maybe she trained to fight in a "flashy" manner over at her adventure school. It wouldn't be out of place in the story that pairs adventurers based on likelihood of boinking
Ignoring the various holes in that sort of plan, wouldn’t it be easier to just… invest in society to try and improve their training instead of just telling them to fuck?
Also even if they do seggs, if the goal was really to ''make babies'', the mother will have to immediately take a maternity leave. Theres no point in hoping for descendants if the woman already ded while adventuring
If you don't know a lot about it Eugenics does sound like a good idea. The main problem is that you can't actually do it with human beings because there's no other surviving member of the homo species. You see when it comes to Eugenics something you have to worry a lot about is inbreeding. And without there being any other members of the homo species there's no way to deal with the inbreeding meaning any attempt at Eugenics will always fail.
Clevatess, bastard!!, Helk, Volundio and so on. They have to be hyper specific about their name because the content is bland. isekais feel less about adventures and more about checking points. Why do they get so specific about their title? Because a single word title requires more depth, so more effort put into.