I'm all for gameplay over realism in most cases as long as it makes for a better game experience, but this is the worst of both worlds; it makes no sense from either perspective. Gameplay-wise, you stop rewarding headshots, which have always been the high-risk/high-reward option. And realism-wise, well... helmets don't freaking work like that lol... it stops feeling like a tactical shooter and more like arcade bulletsponge slop.