Regarding concussion / CTE safety, I think Art Briles was ahead of the curve in one aspect. (Compartmentalizing here, because the dude is a genius football coach.) His teams had very limited hitting at practice. I don't think anyone could say that his teams lacked aggression or were soft, so I'm thinking that you don't actually need to hit each other much in practice to be good at blocking, tackling, shedding blocks and breaking tackles.
The revolutionary mind on this approach was John Gagliardi, a legendary DIII coach at St. John's Minnesota. More programs would be wise to adopt his ideas.
http://www.wbur.org/onlyagame/2012/09/08/john-gagliardi-football
He started this approach in the 1950s and you can imagine how much against the grain his ideas were back then. But he won. A lot.
"I'm not sure that hitting teaches it better because when you're hitting, kids aren't necessarily focusing and doing things the right way," [former player, disciple, and Eden Prairie HS head coach Mike] Grant said. "We also are really concerned to not have kids have long-lasting physical problems."
Chief among those concerns are head injuries.