I wonder if the reason why she doesn't have that many editorials is because she looks much younger (most of the time) than her already young age. (By "young," I mean looking under 16). I know that there's other runway models who are that young or who look that young, but usually the models I see in magazines or in ads are/look over 18.
Lily Cole and Gemma Ward both have had a lot of success when they were young, but they have such odd faces (I like both of them so I don't mean that as an insult), that they don't really remind me of young girls I've seen. They both have an unreal quality about them, that makes them seem like dolls or aliens. I like Chanel too, but in many of her pictures, she reminds me of an 8th grader.
(Oddly, the other models I can think of that looked young in the past had a sexual image i.e. Brooke Shields, Natalia Vodianova, Kate Moss, Lonneke Engel...)
Chanel has a cute, little sister vibe. She's good at making the clothes look young and fresh, but sometimes she makes the clothes look a little too young and depending on the designer, that's not a really good thing.
I doubt they expected her to do every show considering she only did 
