I feel like Marc is using models who aren't typically high-fashion because his lines aren't marketed towards the high-fashion market the way others are. He has an online shop, he's marketing to the masses so using more common, recognisable faces help him to reach the teenagers with daddy's Amex market much more easily. Face it, a Jenner has a lot more appeal to most people than a Russian supernova would, and since Marc by Marc appeals almost exclusively to teenagers and Marc Jacobs to 20-somethings and young 'hip' parents of teenagers in the North American market he's made a very smart move putting her in the show. Lily McMouthamy did the Benetton fall collection with Chloe Nørgaard so I really do see this working well for him, even though whichever Jenner this is (they look the same to me and I really don't give enough of a fuck to learn their names) is basic, she'll bring in so much business for him.
Also, she looks like she's gradually going to become Kim, she looks almost thick already but it could be the clothes. And the hair makes me laugh. Okay done.