Since you asked the question of what role I think the ground rod plays in an electrical circuit... let me ask you.. what role does a grounding rod play in a circuit if it is bonded to a switch box panel, transformer, or whatever it may be attached to?
I do understand that if a hot wire contacts a metal dock the dock and thus the earth becomes energized. It is the ground rod that conveys this potential energy to the earth. This is where the circuit is no longer in the neutral wire but the dock and it's ground wire becomes the circuit in question. I also understand that the "safety ground" is the ideal way to return the electricity to the switch box panel.. which would then convey it to the earth ground or neutral if the neutral is bonded to the ground wire. This is why I asked the question which you did not answer "should the neutral be bonded to the "safety ground/earth ground" at the dock so the electricity can return to it's source? I totally understand that the earth is like a huge resistor and there will be an electrical gradient around an energized dock. However, if a dock is isolated and is charged and you are standing on the dirt or in water and grab that dock then you're gonna get a big jolt of electricity. If you have that dock attached to a ground rod then you are not going to receive the full force of that shock. I would say that this is analogous to not contacting any kind of conductor and grabbing the hot wire and not feeling even a tingle.
One thing I remember from my childhood was reading a story in Reader's Digest of how this person was writhing on the ground which was charged with thousands of volts of electricity from a downed power line. This is analogous to what you are describing.
What I'm trying to figure out is how to safely get rid of that Tickle/ants in the pants when the ground wire from the box with a door on it which is hundreds of feet away is attached to the dock. I already know why it exists which is something you seem to be overlooking. This is the equipotential ground you started out talking about... but apparently this does not remove the ants.