I think the above points made are very strong. I also think that Fitzgerald might be suggesting that the sophisticated world of social manners involves a different set of standards for women. It is interesting to witness that in the story, when Bernice wants to become attractive, Marjorie gives her a cosmetic makeover and demands change to be more appealing to men. There are some definite strands of "Pygmalion" in reverse here. Men don't tell women how to become "socially acceptable," but rather women do the work for men to teach other women how to become "socially acceptable." Fitzgerald, writing in the advance of the Suffrage Movement in the early 20th century, seems to be making a comment on how social conceptions of "being a woman" might have to undergo some alteration in order for women to assume stronger autonomy over their own identities. It's interesting to see the story in this light. The ending with the cutting of Marjorie's hair and the throwing it on Warren's doorstep might be the ultimate repudiation of this growing sophisticated world that is a front for another form of male control over women.
This short story by Fitzgerald is a parody of the social moeurs of the rising social class in the New England states more than anything else. The author intentionally makes his characters rather ridiculous when such banal decisions as what to wear to a party and how to wear one's hair take on giagantic proportions.
Remember that Fitzgerald, issue of the upper class, was disgruntled with the superficiality of values of the nouveau riche and even seemed to be obsessional about what he considered to be the loss of the American Dream. His unhappy marriage didn't help matters either, as he spent a lot of time, money and energy to help his wife who was neurotic.
This short story is quite light-hearted in tone and is meant to be taken as a spoof or joke. Along the same themes, Fitzgerald gets much more serious in his novel The Beautiful and the Damned in which the main characters follow the course of self-destruction much as in Flaubert's Madame Bovary.