I agree wholeheartedly with most of what you say but I don't know that Lidar as a technology will be required if other vendors can prove that they are able to execute without it.
Where Lidar provides superior capabilities to visual/radar/ultrasonic sensors is in situations where the visual cameras, much like a human, aren't sure of what they are looking at.
Scanning ahead and seeing a pothole that could damage the car is trivial for LIDAR but is not easy for a camera system to figure out. Even humans with thousands of hours of driving time have a hard time making this determination.
Another example I can think of is the number of times I have approached a stop sign where the sign is partially obstructed by overgrowth. With visual sensors it is possible that the car is not going to see enough of the sign and see it clearly enough to know it's a stop sign. With LIDAR the sign can be scanned at high speed from a good distance away and the car can then match that partial image and know immediately that it's SUPPOSED to be a stop sign even if visually it's obstructed to some degree.
Another area where LIDAR offers some real advantage is in knowing what is "normal" in a particular area and comparing that known map with what the LIDAR is scanning. This super high resolution map that can be compared with what the LIDAR sees might ultimately be what is needed to safely navigate complex urban areas with narrow roads, convoluted entrances, exits, alleyways, etc.