I think in 2nd gen, these companies having this mindset that fangirls will go to boy groups and fanboys will go to girl groups, so their focus at that time were to attract males audiences for their gg. We all can see how their concept back then were too focus at that.
I have noticed something change in 4th gen girl groups landscape after Blackpink and Mamamoo success that I believe most companies takes a lesson from. From the big 3, Bp vs Twice. From non big 3, Mamamoo vs GFriend. I don't think I need to explain this.
Then now all gg from big 4 all focus to attract female audiences. These companies know that fangirls are more loyal and willing to spends money on their faves. That's why boy groups usually having longer careers. So, tbh I don't see sexy concept will cb to kpop at least not in this gen or next gen.