Elon has mentioned that the reason they are getting rid of Radar is the conflict caused when Radar visualizes one set of data, and Vision reports a different set of data. Lots of time and processing is necessary to sort out which data set is going to be used to direct FSD commands.
This lag consumes a tremendous amount of data for logic to determine which data stream will be best used to direct your car.
The decision has been made that Vision is the most advanced and has the highest potential to effect FSD. Logic would lead them to develop a visual system most like what humans are using (two eyes) to provide the data to the CPU (brain) to direct the best path for the car.
That is why the radar is being eliminated.
Doing so will reduse cost, free up space for other electronics, reduce power consumption, eliminate conflicting data points, save weight, make frontal crash repairs less expensive, and focus all engineering talent and asset on optimizing Vision based navigation.