Each to his own. Karsh had the ability to look deeply into his subjects' personalities, can't deny that. And what you saw was sometimes not pretty but it was usually remarkable. And he did not much alter his style or presentation for gender. Women got pretty much the same treatment as men. And nobody was asked to say "cheese" although they were free to do so.
Was the Marilyn photo cruel? I don't know. It sure was prescient. Maybe she liked it, by that point in her career Karsh must have had to sign off on right of approval. I think I recall hearing it was not released in her lifetime.
Nice Irving Penn quote... "Sensitive people faced with the prospect of a camera portrait put on a face they think is one they would like to show the world. ...Very often what lies behind the facade is rare and more wonderful than the subject knows or dares to believe." In googling "karsh photo" I noticed the largest portion of smiling people in Karsh photos are comedians, cartoonists, and other photographers. Ansel is only kind of smirking.
And seriously, Audrey Hepburn looks absolutely fab in that shot! Dignified, intelligent, beautiful, elegant. Not even trying to hide her nose. Or maybe there are just too many naked women streaking around the web these days, and clothing is the new eroticism.
Anyway, my apologies to the OP. The idea of "copying the masters" is one that should get some airing here. It's a grand tradition now largely held in disdain, but is there some value to it?