Science, that's why. The corners should not be optional. The corner is welded to produce the shape. When you weld tempered aluminum, it causes the material to transform back to the un-tempered state and is a fair bit softer and by virtue of that softness more susceptible to damage.
It is not an issue of material selection either. It is an issue of location on the vehicle and where you intend to play and how hard. Steel in weights light enough to be tolerable or 1/4" and 3/16" in similar designs suffer the same fate.
View attachment 260276
You can see one of the problems I solved where similar design bumpers get bent upwards at the lower edge. The corners get tweaked upward which the corners really help to mitigate on the Savvy bumper.
View attachment 260277
It even happens to rear steel bumpers.
View attachment 260278
If you are going to play in the rocks, the penalty for doing so requires creative solutions, not lots of weight thrown at the problem.
That and who the hell ever said that they are the greatest bumper ever?