field hockey is not as violent as ice hockey and they could implement the same rules over. I believe Rugby too is not as violent as American Football but I guess less exciting ? (I don't watch either so don't know).
There is certainly a growing awareness of head injuries in Union and League at all levels. Players which show any sign of head trauma are (should be) immediately removed from the field for a 10 minute evaluation. However, having played Union for nearly 20 years (from the age of 14), I can attest to the fact that there are many occasions where a head clash occurs which doesn't result in concussion, but still can't be very healthy.
Besides head injuries, I've required an ACL operation due to Rugby injury. My shoulders and back are also in pretty bad shape. I now have a young son and am really trying to steer him towards cricket rather than Rugby.
The period of constant scrums was an especially dull period, as was the rolling mauls period. I vaguely remember a period of constant punts from each side down the field. I haven't kept up to date with Rugby, but google seems to suggest boring rolling mauls are back.
As an Englishman, I still have to say cricket is one of the most boring sports to play, with only 3 players in a team of 22 doing anything even vaguely interesting at any one time (batter, bowler, wicket keeper, 9 other players are literally sitting doing nothing and 9 others are standing around).
It's less a sport and more an excuse to lounge around.
For all it's faults with prima-donnas, football is one of the most engaging team sports with much less risk of injury than rugby or ball-in-the-face field hockey.
Do you mean Association Football there, ie "soccer"?
Regarding cricket, this too is an evolving sport. The emergence of T20 (20 overs per team) has a completely different appeal to 5 day Test matches. Try watching a game of Indian Premier League (IPL) or Australian Big Bash cricket. Batting is back in the ascendancy, with sixes and fours galore. Very much mass appeal, light sporting entertainment.
It's heading the ball that's apparently the biggest source of concussive damage in football.