In my view professional football has over emphasized hitting at the cost of the overall quality of the game. My take is somewhere along the line coaches began teaching their players to hit rather than tackle, probably thinking that the ball comes loose sometimes when a player is hit really hard - and sometimes the player is knocked out of the game. Not a bad theory actually because we all know the leading indicator of wining football is turnover differential, however I propose this is a short sighted view.
Now imagine a football universe where tackling, wrapping up, is emphasized. Sure, you would have fewer loose balls and possibly more completed receptions but your players would not get hurt as often.
Players play longer.
Teams today all run about the same schemes. Why is this? Copy cat league to be sure but I think this is an indirect result of the shorter playing window of the average player. You simply cannot teach a different system to 10-15 new players every year. So you keep the core system pretty much the same as everyone else with some terminology and signals which are unique to your team so you can plug new talent in as needed. If the average player could play effectively for say 6 or more years as opposed to 4 or less, imagine the possibilities. You could have more complexity, more gamesmanship, not to mention players continue to mature and get better at their craft. Ultimately you have teams that look and play differently, teams take on the personality of their coaches and GMs and you have a real competition of philosophy and ideas.