Do the units that you use when you’re setting a velocity for a motor actually matter? Also, is it true that trying to set the amount of current given to a certain motor is in any way superior to setting a velocity?
Matter in what way? If it’s about performance, you can get the same performance regardless of units. You just have to change the numerical part of the velocities when using different units.
No one does current control to control motion of the motor. You might be thinking of voltage control, which controls the potential for applied power directly, but the current provided by voltage control changes based on the current speed of the motor. The other thing that could fall under “current control” is the maximum current limit that the motor is allowed to draw, which supersedes any attempts at voltage or velocity control. You would do voltage control if you are dissatisfied with the built-in PID of the motors, or current limiting if your motors are regularly overheating.