but in some ways it is about reducing the number of bad calls.

One beef I have is that the WHOLE play should probably be reviewed. In one game the Chicago Bears challenged a call about a complete pass by the Packers. In the original play, I saw a 15 yard face mask penalty committed by the Bears that did NOT get called. So if you wanna undo the officials bad call about the completed pass, then why not also undo the officials bad missed call on the face mask penalty. It was clearly visible on the film.

Yet the officials took away the completion, the Packers punted and the Bears won the game. That challenge and that missed call were kinda key.