And opera is pretty special. It's different from any other art form, for instance, meaning that we would lose a cultural dimension in losing it.
How is opera a different form a Broadway musical? Both are musical dramas. The only differences I notice are the language that predominates and how long ago they were typically penned.
Opera is similar to musicals, yes. But in opera I'd say the music is much more at the core of the performance than is the case with the musical. Also, while most operas are tragedies dealing with heavier subjects most musicals are comedies. Not saying one is better than the other but the usage of music and the whole experience is very different.
Tell me, would you consider operettas such as those by Gilbert & Sullivan or by Strauss to be opera or not? What about Porgy and Bess, Candide, Jesus Christ Superstar or Evita? And what about opera buffas such as Don Giovanni, The Barber of Seville, and Falstaff? Other than the lack of spoken dialogue (a trait used by some Broadway musicals) I'd say your definition is highly subjective, but then I doubt that any definition trying to demark which musical dramas are opera could be anything other than subjective.
I suppose you can guess by my name where I stand on the artistic merits of Gilbert & Sullivan, and I'm listening to the
Candide soundtrack as I write. I will say that George Gershwin (
Porgy and Bess) and Leonard Bernstein (
Candide) can both claim to be just as serious composers as Verdi and Puccini. In fact, in the
specific, unique case of
Porgy and Bess, one could say that the work itself is a crucial part of American history and culture, and for that reason alone, merits preservation and government subsidy. After all, it's undoubtedly the most famous and influential opera ever written on this side of the Atlantic, and one of the first shows to ever feature an entirely black cast.
Oh, and Sir Andrew Lloyd Webber, for better or worse, doesn't need public subsidies.