Why does the gyro need the ADC?

[KenWittlief]

the ADC would be inside the gyro itself, with the data sent to the robot controller digitally.

the biggest advantage of this for robotic applications is that its easy to corrupt an analog signal on a wire that is running through a robot chassis. Esp if the wire happens to run along side the power wires going to motors. To keep an analog signal clean on a long wire you really need to use coax cable (which our electronics are not wired for).

Noise injection on analog signals can be very difficult to debug and isolate. You could, for example, have a steering control system that works very well most of the time, but acts up when some unrelated function is operating, like when the compressor turns on, or when a motor is under a full load.

A digital signal is not as easy to corrupt, and if it is corrupted the first effect is dropped data bytes here and there, not noise injected into the signal.