Broadway still seems to be churning out musicals, but I can't say how good any of them are. I assume they have some pretty good performers though.
You need a certain level of competence to be a good musical director. True, not everyone is Busby Berkeley. But the most successful musical director of recent times, Rob Marshall, would struggle to reach Mark Sandrich's level, let alone George Sidney.
As for auteurism, compare
Anchors Aweigh to
On the Town and tell me all you need is Gene Kelly.