These?
WeatherTech Weather Deflectors shield open windows from wind & rain
The ones I've seen probably hurt a bit - they increase frontal area slightly and Cd. The wost ones are the ones on cars where the rear window guard sweeps down with the roofline, so the open area is facing the air flow.
But as you say, you have to decide what you want to keep on and what to remove. People have different wants, needs & abilities and can't delete every excrescence for the sake of driving that perfect tear drop!