Your first argument is the same argument used every time new technology comes out. Friction shifting? Why do I need friction shifting? I can change gears by turning a lever on my seat stay. Indexed shifting? Why do I need indexed shifting? I can change gears by turning a lever on my down tube. Electronic shifting? Why do I need electronic shifting? I can gears by turning a lever on my brakes. Automatic shifting? Why do I need automatic shifting? I can shift gears by pressing a button.
After setting up a computer for different types of rides based on power output, heart rate and any other inputs there may be, and then you need only to choose 1 before the start of your ride. Seems to me it would be an excellent tool for training.
False analogy. Those other innovations were improvements.
In this case, it appears that it would cause problems by putting you in a gear that you may not want to be in.