Though at first glance it looks like the United States is trying to "get away" with something by doing this, it's not that simple. Aside from the strategic factors mentioned in the article, there are other factors too. Much of our nuclear weapons manufacturing infrastructure has dwindled over the past decades*, while test bans and other factors contribute to the great difficulty in making new warheads. If we destroyed our warheads, and then needed many new ones in some kind of emergency, there might be lead times measured in years, and we could be out of luck.

And damn straight the U.S. should possess overwhelming military superiority.

*Even building plutonium power sources for spacecraft has become a non-trivial problem.