People will always try to do what's popular regardless of how overdone it is. It's why every isekai anime ripped from Sword Art Online for a while (many still do!). Yet, SA:O wasn't even a unique concept in itself its just the one that got popular.
It may be because it's an anime, which means people can be attracted to the character design; Western Superheroes are getting boring; a case of liking barely legal characters and lewding them.
@Tjf No. I mean like the superhero academy hero in training thing. This is coming from me. It's totally gay. Every fucking tabletop superhero game now is the superhero highschool thing. I hate it.
The same idea probably applies. Tabletop games pull a lot from pop culture and the ripples that MHA made were pretty far-flung (to the point where non-anime nerds knew what it is).
I supposed I'll just give my thoughts and Occam's Razor: It's popular, it has lots of fans, and you have a template. The Media isn't creative anymore, more focused in pushing an agenda than telling a story, so why not formulate it like it's some step-by-step guide on how to become a successful story, get paid, and never talk about it ever again.