Giving teams a way to measure the amount of current going to a motor could be extremely useful in numerous situations, and would also help teach at least basic electrical principles which seems largely to be lacking in VEX.
I can think of several uses for such a sensor:
Ensuring the current sent to a motor isn’t enough to cause the PTC to trip or overdraw from the Cortex. This is fairly self explanatory, if a motor is drawing a lot of current for a sustained period of time, you want to turn down the power before a PTC gets tripped.
Detecting if a motor is actually connected. If there is zero current when the motor is set to 127, it’s pretty clear that something is wrong with that motor. Drive code could be written so that if one motor on the left side was to become disconnected/inoperable, the corresponding motor on the right side would automatically shut off so that the robot drives straight, albeit slower.
Telling if one motor is doing more work than the others. If one motor on my arm is drawing a lot more current than the others, it’s fairly likely that I’ve done something wrong assembling that arm, or that it got hit by another robot in such a way that a piece of metal is now pushing really hard on a gear it’s tied to, increasing friction.
Additionally, right now VRC tends to treat the electronics component of the robot as magic. The Cortex is a black box that you plug code into that causes motors to turn. The wires carry the magic from the black box of the cortex to the black box of the motors. If you get in a pushing match the magic black box stops working so well and the motors stop turning as fast because… magic? While more advanced teams may know that the PTC is the reason that the motors stop working after a pushing match, they still have no real way to interact with the system and get any meaningful data regarding the black boxes. By adding a sensor that can measure current, teams will have the opportunity to learn more about how the electronics powering the robot work (because doing so will help them be more competitive). Future mechanical engineers are learning mechanical principles designing the robots, future computer scientists are learning programming principles programming the robots, future electrical engineers really don’t have any good reason to learn electrical principles, because VEX has basically already done everything electrical for them.