I think we are all agreed grounding (arching) the aircraft will not protect against lightning. However, aircraft plugged into ground power provided by motor/generators can provide a big surprise. One graveyard shift where most weird things happened, we noticed a long tongue of fire erupt from the ground wire connected to the nose gear of an L-1049 Connie. It was the accumulated oil burning off then insulated ground cable. The aircraft was on the fence plugged into a 28V DC motor/generator powered by 3ph 440V. AC. Insulation had failed allowing one leg to connect to the neutral leg of the 28V DC power. A/C was happy, it couldn't see it. Ground wire did.
Power cables also can have faults. I personally think ground iris are. Good idea.