It's a practical choice, not an artistic one
That's a very good point, and well made. I thought about this, and my reasoning for this "stormtrooper helmet" trope was so that the protagonists don't look like murderous psychopaths while dispatching of rows and rows of henchmen, and there is no chance of emotional connection between the viewer and the henchmen. This is also why zombies; they allow the heroes to kill dozens, hunderds of people, and we still don't register them as people, just people-shaped objects.
On a sidenote, I really enjoyed your review of Lying for Money! Good work!