What Value is the "Foul Tip Signal"?

[tcannizzo]

We all know what a foul tip is. But what is the value of the signal with the finger tips?

If the catcher doesn't catch it, we have a foul ball.

If the cather catches it, we have a live ball.

Since the ball is live until the umpire gives a dead ball signal, why is it necessary to signify that the ball is live? It is wasted motion.

I am not questioning the rules and effects of a foul tip versus a foul ball, but questioning the need to signal it.