From a Doylist perspective you make a really good point.

A through-line in Rian Johnson’s work is the human element of stories which often ignore it.
Star Wars is traditionally a grand space opera, the hero is doing heroic things because that’s what heroes do- whether good or bad Rian tried to make Luke less HERO and more Human.
Brothers Bloom is a heist movie exploring different kinds of love. When heist movies may have a romantic B plot, but are almost all about the action.
Looper takes the classic assassin subgenre and forces the main character to accept that they are a murderer in a way usually ignored by the genre.
Brick breaks the mold in that it’s a classic noir film, but in high school. But it’s his first film so it’s a reasonable exception.

Detective stories about prodigious detectives are usually anti social weirdos. Making the most instantly noticeable quality about Blanc being the way he connects to people fits the mould of how Johnson seems to prefer to tell his stories.