When the people who make Necco Wafers changed their recipe to use natural flavors and colors in 2009, they thought they were doing their customers a favor. But then those customers told the New England Confectionery Company — loudly, and repeatedly — that they preferred artificially enhanced candy. "Our normal mail volume probably went up twenty-fold" after the change, says Necco Vice President of Research and Quality Jeff Green says. "Some positive, and some negative. But a lot of negative." The common theme from Necco's longtime customers, Green tells NPR's Michele Norris, was, "You ruined my product, I will never...