Sometimes it is better to have squared off edges than rounded ones.
Might sound surprising, but it makes for cleaner flow detachment, and makes the flow more predictable (so you can manipulate it a little easier).
yes I see what you mean. For a team starting from scratch, it is wiser to try to understand the behavior of air moving around rather simple shapes instead of trying to come up with a very efficient thing while dealing with complex geometry they haven't tested yet.
But Toyota are five years old now, they have a wind tunnel running flat out like others, why aren' they trying to evolve the desing, at least testing it. In the end if the "squary" design is that efficient, why are other teams trying that hard to avoid it?