A lot of those are aimed at teenagers who haven't gotten tired of that yet because it's new-to-them. That is both boring and an excellent business strategy. Plus it's not like it's easy to write flat characters if you're not an experienced writer, so people have to start somewhere.
It's however not like we're rolling in in series similar to this one like we are with low tier het vanilla harem manga, so I can't blame anyone for not being bored of it yet. I certainly haven't seen another yuri story about an otaku beating up a group of gyaru bullies and forcing the gyaru MC to play out the otaku's defiled night fantasies and similar.
As an adult that's well versed in a lot of stories I still found these 3 chapters entertaining, though maybe it'll become too dark and violent for me down the road. I don't think everything has to be complex and deep, there's room for a variety and sometimes a simple raunchy dark comedy is fine.
I think--and this is me personally, to be clear--it's that we've hit the ground hard on what gimmick is in play for the premise of the series: one-sided physical and sexual violence from the "bullied" to the "bully" that sees the latter eventually fall for the former. The physical violence is entirely played off as a gag, and the sexual violence causing the gyaru to already start 'physically falling for' the otaku isn't really all that far removed from your average hentai "plot" that sees a woman pressured into sex until she starts to like it, whatever proclivity or rationale she might have had before.
And that's basically what we have. We have some small tidbits that are outside of that--the otaku's working on a manga series, and the gyaru was seemingly Top Dog at her old stomping grounds before she showed up at this school. But three chapters of the same basic sequence of events--Otaku beats up Gyaru, then sexually abuses Gyaru, and Gyaru gets flustered and starts questioning why she sorta likes it--and that formula, while titillating, doesn't seem like it could go on for too long before even those who are looking for it grow bored.
Again--it's three chapters. I'm more than happy being proven wrong, and given the lackey's just found out about what's going on, perhaps there'll be more depth in the coming chapters and I'll be completely off-base in what I've said here and before. But I would also be correct, in that something more was needed to see this have any legs as a long-form series.
It doesn't have to be complex, sure. But to me "complex" doesn't mean that there shouldn't be any desire to remember a character's name or care about what happens to them over the course of the series. A "simple raunchy dark comedy" isn't mutually exclusive from three-dimensional characterization.