The arguments by American critics of a gold standard all rest on this unstated presumption: The economic outcomes of policy decisions made by a committee of 12 salaried bureaucrats, 7 of whom were appointed by the president of the United States, and 5 of whom were appointed by the largest regional banks that own a majority of shares of the 12 regional Federal Reserve banks, are better for the nation than the decisions of millions of owners of gold coins, who seek their own interests.
This is the argument in favor of a salaried bureaucracy in place of the free market. It assumes the superior wisdom and superior public interest of a committee of academics (Board of Governors) and commercial banking agents (regional Fed bank presidents). The mainstream opponents of a gold standard never put it this way, but this is the inescapable implication of their opposition.
Ultimately, this debate is between the logic of the free market as a social organization versus the logic of central planning. The battlefield is monetary theory and monetary policy.