I can think of one huge advantage of not having it--without it, you never have to worry about an [censored] at the dealer lifting the wiper arm up (to clean the back glass) and allowing it to fall down, which puts a nasty scratch in your paint because the wiper blade pivots far enough that the corner of it hits the painted framing around the back glass. Worse design ever.
I had the scratch fixed twice, no joke. They did it the first time, and had it repainted. While cleaning the car up after the repaint, they did the exact same thing and scratched the car again.