I'm guessing here, but I wouldn't think there is much (if any) performance difference to this new design.

BUT! Look at it from the manufacturing point of view! You are now using 15-20% LESS material in the "mushroom cap" because of those radius cutouts and probably charging the same amount if not more for this new product! Make a new mold, use 15-20% less material, and charge the same. Nice deal for them-