Today, the U.S. Treasury released a $1 coin commemorating former President James Buchanan. And people aren't happy about it. To understand why, some background is helpful. In 2007, thanks to a bill promoted by then-Senator John Sununu of New Hampshire, the Treasury began minting $1 coins with the likenesses of former Presidents, starting with George Washington. The coins -- which have been appearing ever since, featuring a new President every three months -- are meant to improve use and circulation of America's dollar coins, which are often seen as an awkward misfit among currency, neither fish nor fowl. Sununu's initiative...