Any decent DB, not looking at the ball, is taught to react to a receiver's movements and them slowing, starting to drift back, is a sign the ball is probably going to be in 50-50 territory.
Sure, you could get the PI or they could get the PI. Granted, usually it goes to the offense.
You could also get a turnover or incompletion by the DB making a play.
I don't like balls thrown so the DB only has to turn to have a reasonable shot at the ball. I see your point but I'd never want my QB to err on the side of short throws.