These initiatives of the NFL are products of lawsuits and unrecoverable head injuries.  As you say--
 no one is ever taught to tackle with their head-- and yet brain and neck injuries will always persist, because incidental and unintentional hitting of those areas occurs in just about every play.  Our kids will never play football-- when there is baseball, hockey, soccer (by far the best for kids, IMO), and other team sports which are infinitely safer, especially over the rest of the life of the child.