Not only that, the *ball* is off the ground, which I think would create the same issue. I've noticed in a lot of their product photos that the shoes seem to rest somewhere between the ball and the toe.I wouldn't daresay it's the main reason, but one of the causes is because that front part of the heel is off the ground.
I have been saying this for ages. When stepping on the shoe, the heel is forced to lie flat, pushing the quarters up. Resulting in the bowing you see around the ankle, which is just above the heel.