So Nicholas Hytner decrees London’s National Theatre won’t be producing the big flashy musicals anymore. “This seems, at first blush, somewhat dog-in-the-mangerish of him. As a guest director, he was responsible a few years ago for a production of ‘Carousel’ that ranks as one of the National’s most successful and enlightening musical revivals. It’s as if, having had his fun, he’s all set to stop other directors – not to mention other audiences – having theirs. He has a point or two, though.” These big musical revivals – do they really work artistically?