Never underestimate the importance of a dancing teenage girl. The smart, wary high-schoolers in Kimberly Belflower’s inspired “John Proctor Is the Villain,” now in a world-premiere run at Studio Theatre, may look as if they’re just bopping around to the music of Lorde and Taylor Swift. But their moves — and gripping, funny talk — cast light on urgent social concerns, from the patriarchy’s grip to the implications of #MeToo, to widespread deficits of trust. And if the kids can blow off some steam in the process, that’s a plus.