alt Hacker NewsIt adds a sort of tragic element to the game. Growing up I used to cheer for big hits now there's a recognition you are often watching someone lose several years off of their life.
There's also these guardian caps to reduce some of the shock, but they're not very effective - they absorb like 10% of the blow, and you don't see very many players wearing them in-game.
The main issue seems to be shock to the brain being sloshed around inside the skull, even neck-snapping type impacts without any contact to the head itself can cause brain injury. The extra helmet padding doesn't do anything to reduce that. Plenty of linemen have been diagnosed with CTE even though their play doesn't involve as much helmet contact or high speed collision.