I agree that some players -- Gronk and Newton are the best examples I can think of -- make it hard to call the game the same way because of how physically gifted they are.
In that situation, I'd prefer to err on the side of calling the rules in a way that allows the offensive player to make plays, rather than allow the defensive players to resort to extremely dangerous tactics that can take the offensive player out of the game entirely.
The analogy I'd make to the NBA is players like Shaq -- would you rather watch Shaq score 50 on 70% shooting, or watch defenders endlessly hack and foul him? I don't like either option, but I'd prefer the first one. And in football, you don't get free throws. At the very least, these types of hits should result in a 1st down and 10-15 yards.
I really don't think this is so hard to identify. Defensive players should not be allowed to "launch." Period. It's dangerous for all players involved. You make a good tackle, or you don't. You don't lead with your helmet, and you don't turn yourself into a missile to try and knock them down.
This should apply to offensive players, too. Far too often I see offensive players lower their helmet toward the defender when they can see they are about to get hit.
All of this, I believe, is why some studies have indicated that football is actually less dangerous when the players don't have helmets on. When you don't have a helmet, you actually try to protect your own head!