The practise of grounding HV conductors is not one of trust but one of necessity. Except on distribution radials, there are typically parallel circuits, these parallel circuits can energize a nearby isolated conductor by mutual induction and capacitance. Capacitive coupling will impart a voltage on an isolated conductor. Grounding at one point corrects this. However when you have a conductor grounded at one point, the mutual inductance with parallel current carrying conductors creates an open loop (the ground is the other half of the loop). There will be a large potential at the gap that closes this loop (the gap is between the conductor and your hand if you are in a grounded bucket). This is why a ground is installed at each end of an isolated section of line.
