Ground plane on dual layer PCB, Is plating needed?
You really want the through-hole plating on all holes.  They will be electrically isolated from the ground plane, but they provide significant additional mechanical strength for the traces that connect to the pins and allow the solder to flow through the hole and provide a mechanical connection on both sides of the board.  This reduces the possibility that the pad on the bottom will separate from the board because of mechanical stress or thermal cycling.