I think most of these girls deserve to cover. They have the resume's to earn it.
Doutzen- Calvin Klein campaign, Loreal campaign, Bottega Venata and lots of other campaigns, Vogue covers
Hilary- has done Balenciaga, Givenchy, Donna Karan, Gucci ads and now is going to be one of the faces of Estee Lauder, several Vogue covers
Lily- Burberry, Dior, and lots of other campaigns, Vogue covers
Sasha- Prada campaign for several seasons, Vogue covers, Armani makeup campaign
Caroline- has been in every US Vogue ed ever!!!!
Stam- tons of campaigns, tons of covers
Raquel- I don't see how she is the next top model since she has been around for a while now, but she deserves it.
And all of these girls do the big fashion shows each season. As for Coco and Agyness, I just think Anna likes them.
edit: Forgive me if I forgot some campaigns, but I was writing off the top of my head.