Refs nowadays have too much influence over the game. Their iffy calls or non-calls can decide who wins and who loses.
The best suggestions I've seen, are eliminate the DPI when a WR is coming back to the deep ball. That can't be automatic like it has been. It has to be an absolute mugging. So many WR's just throw their hands up and the refs call it.
Also, the holds, etc.. that are on the complete other side of the field and away from the play. Don't call a penalty like that if the hold has nothing to do with the outcome of the play.