The NFL will never make it a 15-yard penalty and introduce pass interference as a defensive strategy. The NFL wants big plays, and you would likely see a drop in them because defenders would be taught to just tackle the receiver if they are in danger of being smoked deep. I think there needs to be some emphasis on how it's called, though. I see pass interference called too often when the ball is uncatchable, and offensive pass interference is not called often enough. The worst, though, is calling a defensive pass interference for contact that does not materially impact the play. The name of the penalty is pass interference, so you might naturally expect it to be called only when the players' opportunity to make a play on the ball is interfered with. There are plenty of times, however, when it's called even though there's no real impact on the play.