Medlens crash showed that normal pipe insulation foam did not return to it original state when it was compressed it stayed compressed and as the helmet continued to batter the cage from side to side the helmet was striking the cage itself as the foam was useless after the first hit, the oscillation caused the helmet to rapidly strike the cage side to side..
Believe me i am no gore seeker i have seen plenty of the worst n my lifetime, but i do look at footage so my soul can understand the situation and look for an answer to a particular tragedy.
I rarely discuss such incidents with anyone but my wife who loves this sport as much as i do, i dont even talk about it with car owners that r close...
Mandatory???? If science proves a benefit then yes..