Are you muttering ““Who cares?’’ Broadway cares, and so does CBS, whose ratings for the Tony show languish in the single digits. Of course, the Tony folk have been known to fiddle with their precious categories. Last year the compendium of Rodgers and Hammerstein tunes ““A Grand Night for Singing’’ was nominated for best book, even though no book was discernible. Some Broadwayfarers think that a best-score nomination may go to music for a straight play, maybe Wynton Marsalis’s for the upcoming ““On the Waterfront,’’ to fill out the category so that Lloyd Webber can get his Tony. But others say that won’t happen because of envious animus against the Britonaire. Producer Michael David, a Tony administrator, says the awards must be flexible: ““You have to take the things that happened and find some way to recognize them.’’ All this spotlights the eroding of Broadway as a creative force. It’s overdue for the Tony to pull its nostalgic head out of that pile of old stardust and open its doors to the importance of Off Broadway.