The open circuit voltage, that is the voltage at that instant just before the spark jumps the gap, would be the same regardless of how high the resistance is unless that resistance is extremely(virtually infinitely) high. But would result in proportionately lower current flow across the plug for the brief period when it is firing.
Higher resistance, results in lower current flow and the heating of the wires varies as the square of the current so the reduced current would results in much cooler wire and much less deterioration.
If the plug is not fouling, the engine performing well: good economy and all, I would not really care. But I would check now and then.
Bear in mind, please, that my B.A.SC. is ancient.
Malcolm Mason