I don't see this as any kind of "moment in American playwriting." Fearless writers didn't just appear suddenly in the last couple of years. They're always around. What happened is that it became trendy to produce this kind of work in the New York non-profit theaters that champion the work of young writers. By "this kind of work," I mean plays that are essentially about politics, or even about a certain political stance, and just use narrative as something to hang the politics on. These plays exist less to tell a story about people's lives and relationships than to make a point -- about racism, about homophobia, misogyny, religion, capitalism, colonialism, etc.
Maybe it's less a difference of type than of degree, I don't know. A Streetcar Named Desire and Who's Afraid of Virginia Woolf? have plenty to say about class and gender. But you don't leave those plays feeling like you've been to an undergraduate lecture. Whatever messages are there are subtle and, for that reason, I would argue, more powerful, more lasting. If something is handed to us we value it less than if we had to make an effort to find it.
I don't know what's "fearless" about this "new" kind of play. It's incredibly popular in the circle in which it gets attention, wins awards and grants, gets produced. Is it fearless for me to post a clip of Rachel Maddow going off on Republicans on my Facebook page, when all my friends agree with me? It seems to me lately that it's much riskier to not be making explicitly liberal political work, because nobody's interested.
I like some of these plays, dislike some of them, but what I'm waiting for is the next moment, the one where we can get back to telling stories about people, without the need to hammer a political point, without all the dog whistles reassuring us that our politics are correct. Lord knows I love the politics, and I'll talk to you till the sun comes up about the political implications of a play. Racism, homophobia, misogyny, colonialism, religion, and the rest are some of my very favorite topics. But I'm weary of being lectured to in the theater.
Polemic often has to rely on over-simplification in order to be persuasive. But human beings in the world -- which is what I think plays should be about -- are endlessly complex.