George Packer
makes an obvious but important historical comparison:
But it was Johnson who pushed hard on civil rights where Kennedy, assuming he’d get to it after his reĆ«lection, hesitated. And it was Biden who, inadvertently, forced Obama to stop evolving and declare himself on an issue that the President clearly hoped would leave him alone until after November. Though same-sex marriage isn’t a cause on the same scale of historic injustice as the color line in America, it is the issue that forces today’s politicians to take a clear and politically difficult moral stand. It’s an issue for politicians whose egos are not under tight rational control—who are, come heaven or hell, passionate.
Though my favourite comment on Biden's remarks was from Dave Weigel, who
tweeted, "Okay, Biden. Now say something about decriminalizing pot."