Definitely this. NFL defenses are handcuffed enough already. Pass Interference should not be a 40-50 yard penalty.
As for preseason games, I don't mind if they play 4 games, but have all preseason games played in neutral sights. Have the games played at local college stadiums. The college teams aren't playing at that time and you can draw enough interest for some fans to show up.
It also helps season ticket holders out by not getting stuck to pay $250 for a meaningless practice game.