I'm pulling this mostly out of my ass, but I'm pretty sure that to call a fashion model misvalued because of her facial attractiveness is misunderstanding fashion models.
Fashion models are not Maxim models; I'd imagine they're actually actually fairly disconnected pools of talent. There is some conjunction (eg. Sports Illustrated), but there's an availability bias -- most of the fashion models you or I are aware of are the ones who are culturally relevant outside the fashion world (mostly for being really hot). The value of a Maxim model comes from how sexually attractive she is to men. They'll mostly be shorter, healthier and have bigger breasts. Maxim models are also subject to the cultural whims of their audience and their variable loci of attractiveness, not all of them defined by purely physical factors -- Danica Patrick or Hillary Duff, while I certainly wouldn't kick them out of bed, in a cultural vacuum of pure adolescent horniness, would not be in the same league as Miranda Kerr.
Fashion models are frames for hanging art. A weird, angular face may be an important component in the look of a piece of clothing. Art also undeniably interacts with the personal character it's associated with. With most art, that's only in the creator, but I'd imagine that in fashion modeling, most of the spectators who care will perceive a piece of clothing and the character of a show by the composition of the personalities of the models in it. In high-fashion, anyways, where I'd imagine, like in the highest-level in any field, distinction is tuned down to subtle details that neophytes wouldn't even notice: it is crudely and fundamentally complementary to a fashion show or line to be shown off on somebody attractive; but when you get up there in talent, every detail, including the model, must be tuned to some creative harmony, and that value is not at all captured in the sexual attractiveness of a model by herself.
[again, disclaimer: I actually have no idea what I'm talking about. I haven't opened a Maxim in 6 years, I've watched a few episodes of America's Next Top Model, and I'm otherwise a red-blooded Canadian heterosexual male nerd.]