Yglesias is right about how Richard Arenberg's Politico article defending the filibuster is thoroughly confused. The minority rights worth protecting are the rights of minorities among the people. Nobody should care about defending the rights of a minority of Senators to determine policy. Assuming that democracy is operating properly in their elections, there's a very good reason why those Senators are in the minority -- most people opposed their ideas. As happened in the Civil Rights era, a minority of Senators may keep filibustering legislation that would support equal rights for a minority of the people. Then we should support the minority among the people (who likely have backing from a majority of people, which is why they have majority backing in the Senate (setting aside issues about Senate overrepresentation of unpopulated states, which Arenberg isn't interested in fixing)) and against the Senators.
Here I think Arenberg is even more wrong than Yglesias suggests. One great thing about America that should give us optimism is our history of overturning race, class, gender, and sexual orientation-related prejudices. It's not just true of America, but of societies around the world over the last few centuries. Things were worse long ago than they are now, and I'm willing to extrapolate towards their getting even better. If you think this is what's going to happen, you want it to be easier to change the status quo. If you think things are going to get worse for minority rights, so we'd better defend the status quo against change, you might support the filibuster. But I think the last few centuries of history support more optimistic bets.