The US wasn't exactly unable to built a military counter-weight to the USSR, even nuke wise. I would argue rather the opposite. The fact that the US had lesser warheads and delivery systems, as written down in treaties, wasn't due to the lack of american production capability. The US systems just were more accurate, hence they didn't need to launch three to five warheads in the hope one might hit the target. There's no point in turning tundra into waistland.
Furthermore, those warheads are really expansive to maintain. If there's no operational / strategic need, then way put the financial stress on the country to have a 20x overkill instead of a 15x overkill?