Luciano Pavarotti sang his last performances in opera at the Metropolitan this week. Richard Dyer: “This is not the occasion to survey Pavarotti’s nonoperatic career in concert, arena events, on film and television, with the Three Tenors, and as a newsworthy talk show celebrity; all of that continues. What is important is that Pavarotti let all of his outside activities feed back into opera. He could have left the opera house decades ago and made even more money than he has, but he chose not to. The musical world needs its celebrities because they vouch for the validity of the art.”