Read "The Man Who Turned Into a Stick" by Abe Kobo. How does this story function as social commentary or satire?

This story functions as a satire because it makes the argument that most people -- "98.4 percent of all those who die in a given month," in fact -- live such uneventful lives, are so "satisfied" with their lives, that they do nothing special at all, nothing that would warrant either reward or punishment.  A satire is a text that uses humor, irony, and wit to expose human weakness or folly in order to, hopefully, spur some kind of change in the person or people it targets.  The human weakness exposed by this text is that we have, evidently, become too complacent.  As the Man from Hell tells the Hippie Boy, "I'm sure you haven't any particular aim in mind" in regard to the stick, to which the Boy responds, "I'm not interested in aims," and the Hippie Girl confirms, "Aims are out-of-date."  It's as though they (and we) have no goals, at least not any extraordinary ones: that the vast majority of people, in reality, lack goals.
Therefore, when the Man from Hell tells the Hippie Boy and Girl when they sell him the stick for five dollars, "you may imagine you've struck a clever bargain, but one of these days you'll find out.  It wasn't just a stick you sold, but yourself," what he means is that this Boy and Girl will probably become sticks as well; after all, they've already confessed that they have no aims in life.  Just as the man who died was simply "a living stick [that] has turned into a dead stick," so too will they (that or "rubber hoses").  This is why the Boy and the stick "understand each other" in his words and "look alike" in the Girl's.  They are the same in that neither one lives or has lived a life that can be called exceptional or even interesting.  
The stick, as the Woman from Hell points out, is "encrusted with dirt" from being handled so much, that its bottom is "rubbed and scraped": evidence that it has been used, "employed by people for some particular purpose."  She believes that "it [has] suffered rather harsh treatment" as it "has scars all over it."  In other words, this stick, when it was alive, was only a "tool" as the Man from Hell calls it.  Perhaps it was used by others but really had no initiative of its own, no particular and personal "aims."  
This social commentary is rather bleak, however, because it does not seem as though we have much opportunity to change our fate.  The Woman from Hell wants to give the stick to the little boy (whose father changed into the stick), saying, "At least it ought to serve as a kind of mirror.  He can examine himself and make sure he won't become a stick like his father."  The Man from Hell laughs because no one who's truly "satisfied with himself" can avoid becoming a stick.  Ultimately, then, it seems that the only way to avoid turning into a stick when we die is to not be a stick while we're alive: we cannot be too satisfied or complacent.  We must push ourselves, have "aims," and really work for them.  Sadly, according to this story, it seems that most of us will fail to do so.