@Miranox
The author is playing to a particular audience that enjoys this crap.
Like when he shows the MC being too braindead to realize the girls love him more than a friend does or that they get sexually excited when he alters their skills.
The author knows people aren't that dumb but there is a group of people that enjoy that crap in fiction, so by pleasing those people, the author can ensure success for their work.
This is common across all types of fiction. You can see the same thing in like for example horror movies: The hero/heroine forgoes logic to run away from the otherworldly attacker by running away in a straight line toward an obvious dead end.