High voltage also reducses the amount of conductor needed. Heavy industrial motors are often 4160 volts (our plant uses the less common 6,900V). This reduces the current (and hence temperature rise in windings) in not only the motor, but the copper conductors from the switchgear room to the motors.
For transmission, over 100 KV (100,000 volts) is not that high of voltage. Up to the mid 200 KV’s is normal.
