Brake systems have already gone from mostly mechanical/hydraulic to more and more electronic with ABS, radar-autobraking, individual wheel braking with ESP and so on. The drivers brake pedal is just one of many inputs to the eventually hydraulic system, while the other inputs are already electronic. It seems to me you can simplify it but keeping all the brake inputs electronic and fusing them closer to the wheel, instead of having a mixed mechanical/electronic system?

Same as a throttle. That used to be a wire (perhaps it commonly still is?) but the throttle input shifted from being solely the driver into being other systems like cruise control. As soon as you have an electromechanical system it does seem easiest to keep it electric->mechanical rather than mechanical<->electric. That simplification does ignore the driver feedback, however.