I still assert if you take away all (or most) of the armor that modern players have the injuries would go down. All of the spearing, head leading etc would no longer happen.
Personally I think a lot of our injuries were because we had a lot of former football players who were used to a different sport. It takes time to adjust. My "career" (fun hobby) ended from a ridiculous move from an overzealous opponent that destroyed my shoulder. If we were wearing football gear everything would have been fine. I wonder if rugby players in the US get injured more frequently than in other countries because of our legacy of American football.