A more demanding standard for dropping magnesium headforms onto anvils can always be written. I'm certain that requiring cyclists to wear FIA 8860-2010 compliant helmets would drive cycling related head injuries to zero - since the ~$3000 entry-level cost of those helmets would wipe the streets and roads clear of cyclists.

In almost a half century of riding I've seen one (1) cyclist wearing a motorcycle helmet - who, as it turned out, was recovering from brain/skull surgery. However, anyone is welcome to do so if they feel bicycle-specific helmets are inadequately tested/certified.