That's because its not needed. The aero has changed. At any kind of speed, the water just disappears. Put some RainX on the rear window and the water rolls off. Times change, technology changes. It's not just that some people don't like it cosmetically but rather its just not needed. The other day I was on the highway moving down the road in a monsoon rain and the rear window was fine. Now SUVs - totally different.That's the story of the rear wiper to be more specific:
The Unlikely Story of How Porsche DNA Probably Ended Up On Your Car | Petrolicious
I don't see people opting for it nowadays, though.