"We had some licensing issues with him so we weren't able to obtain him for the American version," Niitsuma told Siliconera. Apparently, the original Hakushon Daimao show ran across the world in the '70s, so the holdout could be any number of companies.
Niitsuma said that "new characters" would replace Daimao -- confirmation of the "five new characters" promised on Capcom's press release (which was later reissued with no mention of new characters)? We can only hope that one of those characters will feature Daimao's math minigame. Or not, actually.