I agree with the folks that say there is a difference between an antagonist and a true villain. In fact, I can think of lots of musicals without a villain (e.g, My Fair Lady, The King and I, The Producers, La Cage aux Folles) but, without some kind of antagonist, there is never a successful story, whether that story is a mystery, romance, or sci fi novel, a comedic play, or a musical.
I'm on the fence as to whether Javert is a strong antagonist or a villain, although I lean towards villain. I also wonder how to classify villainous protagonists, such as Henry Hyde, Sweeney Todd, or my personal favorite, the Phantom. Are they villains or are they misguided? Maybe, they're a bit of both.
You alone can make my song take flight.