A 36-YEAR-OLD dentally challenged cellphone salesman wins a nationally televised talent contest in Britain, and suddenly, all sorts of questions are raised about the role of classical music in our world. That is because the winner, Paul Potts, from Wales, triumphed with a rendition of “Nessun dorma,” the tenor aria from Puccini’s “Turandot,” at a contest with the trappings and audience — seemingly — of the mass entertainment world. By the standards of music critics who ply their trade in opera houses and concert halls, it wasn’t a particularly earth-shaking performance. “Mr. Potts is the sort of bog-standard tenor to...