WASHINGTON (Reuters) – U.S. Federal Communications Commission Chairman Tom Wheeler on Wednesday said maintaining four large U.S. wireless carriers was “good for American consumers” after news that two of them, Sprint Corp and T-Mobile US , were abandoning plans for a merger. Sprint “now has an opportunity to focus their efforts on robust competition,” Wheeler said in a brief statement. U.S. regulators, including antitrust chief Bill Baer and Wheeler, have been unusually public about their skepticism of a merger of the two carriers. …