From the Downton Pawnee tumblr.
Andrew Sullivan linked to a couple of different articles trying to explain the (unexpected?) popularity of Downton Abbey in the United States. For Newsweek, Simon Schama makes the case that the show is a snob-ridden piece of Hallmark-y tripe:

There are many things wrong with the Republic in 2012, but when historians come to write its chronicle they will notice that the country was gripped by the clammy delirium of nostalgia. Tea Partiers ache for what they imagine to have been a tricorny country, all innocent of the Monster Government. Politicians and radio ranters sell the credulous on an American paradise before “socialism,” in the wicked shape of Social Security and Medicare, ever came to be. And folks who might have better ways to pass their time have been falling like grouse to the gun before the mighty edifice of Downton Abbey. Deprived of a wallow in the dry-martini and bullet-bra world of Mad Men? Not to worry, Downton serves up a steaming, silvered tureen of snobbery. It’s a servile soap opera that an American public desperate for something, anything, to take its mind off the perplexities of the present seems only too happy to down in great, grateful gulps.

Irin Carmon posits that the show’s popularity resides in an idealization of the class system and a portrayal of noblesse oblige on the part of the “upstairs:”

“I actually think it’s a lot like ‘The West Wing,’” Steve Jacobs, a political communications strategist and a fan of the show, told me. “Lord Grantham is the platonic ideal of an English aristocrat, just like Jed Bartlet was the platonic ideal of an American president. The very fact that Grantham and Bartlet are so good and selfless is, to me, an indication that they’re not meant to be completely accurate depictions of their real-life counterparts.” Even if a democratically elected president differs in earned legitimacy from an earl, both involve a Great Man shaping history. As Max Read, a writer at Gawker, says of the analogy, “Both shows suffer from operating under ideas of politics/history that focus on the individual actor rather than the system. So the nobility and selflessness of Bartlet and the earl justify the systems in which they work … It’s a very classically conservative notion of history.”

Kathryn Hughes interprets the show as a reflection of British social anxieties, and places the show in a line of historical class dramas:

The show’s values of cohesion and cooperation promise to be challenged by the war’s fallout. But they remain Downton Abbey’s guiding ethos. There may be disruptions looming (socialism, feminism, the small matter of international carnage), but if the classes just pull together, total breakdown may be avoided. The creator and chief writer of this careful and approving dramatization of a social unity that depends, paradoxically, on social separation is Julian Fellowes, who was recently made a Life Peer—which means he becomes Lord Fellowes, although his son will not inherit the title—and sits on the Conservative side of the House of Lords. Fellowes is too canny an operator to say out loud that he wishes we could return to the good old days in which the story is set. But as season two approached its close in Britain, there was no getting around an increasing sense of the show’s nostalgic longing for an age of what we might call consensual paternalism. Which is all very well, of course, as long as you’re the one on the right side of the social divide, the side that decides whether it feels like being benign to those less favored than itself.

Obviously I cannot speak for all viewers of the show, and I am certain that there are plenty of them who watch it for the pure spectacle of costume drama, but none of these perspectives quite gets at why I like the show. I agree that the show generally positions the Earl of Grantham as a pure actor in an opressive system, and that the show draws some of its power from societal shifts that are happening right now, but I think it’s entirely too superficial to dismiss the show as nostalgia for a time past.
http://seg.sharethis.com/getSegment.php?purl=http%3A%2F%2Fmtthwkrl.wordpress.com%2Fwp-admin%2Fpost-new.php&jsref=&rnd=1326914289114Most period films have to deal with the moral conflict produced by societal differences between our time and the period depicted. Films can sidestep those questions, either by depicting characters as evil because their time was “evil” (think Braveheart: William Wallace is our enlightened, educated, modern hero, but 13th century Englishmen are mostly evil because they’re 13th century Englishmen), or by idealizing the past and not engaging with the question at all. But most honest films do deal with it one way or another, even if not successfully. And clearly Downton does idealize its main characters. But I think this is a deliberate strategy to highlight the brutality and suffocation of the system they operate in.
The Mad Men comparison is apt. A big difference, of course, is that Don Draper and most of the characters on the show are clearly portrayed as extremely flawed people even in the context of their time. This makes it a better show than Downton, however where they come together is in detailing the lives of a class of people who are going to be absolutely rocked by the social changes that will affect them in the coming years. Just like the social unrest of the late ’60s that invisibly permeates Mad Men, so does the period between wars permeate Downton. And that’s where the idealization of this group of people that inhabit the system becomes a real driver for pathos. Whether or not this class system has value (and personally, I do think the show could come down harder on the side of the “or not”), these people are going to have their lives completely upended, and all of the norms that they have internalized through their lives are going to be called into question. Even these people.
To be fair, Schama acknowledges this point:

In the current series, historical reality is supposed to bite at Downton in the form of the Great War. The abbey’s conversion into convalescent quarters did indeed happen in some of the statelies. But if Fellowes were really interested in the true drama attending the port and partridge classes—more accurately and brilliantly related in Evelyn Waugh’s Brideshead Revisited and Isabel Colegate’s wonderful The Shooting Party—the story on our TV would be quite different. Instead of being an occasional suffragette, Sibyl would have turned into a full-on militant, carving, while incarcerated in prison, a “V” for “votes” on her breast with a piece of broken glass. Lord Robert, whose income from land and rents would have collapsed with the long agricultural depression, would be unable to service his mortgage and, subject to the estate duties imposed to pay for old-age pensions, would have to sell the place to a wheat baron from Alberta. And Matthew would be one of the 750,000 dead.

and I do think he has a point. Fellowes class affiliations should be called into question. And there’s plenty of time for the show to go on too many seasons, postponing the painful social change until nobody cares any more. But for now, that spectre of change, visible only to us, hovers over the show and I cannot wait for that other shoe to drop.