We use it on the ground (for the Dash) mainly to keep airflow in the cabin, which can get very stuffy even on a cold day if you've got 70 odd passengers on board.
Also, we have pushback starts at our main ports, so require APU on for engine start on pushback.
IMHO, noise on the ramp should never be a consideration for NOT using the APU if you require it. Ramp staff should be wearing PPE.