In any case, there has never been a time in American history when the alleged personal traits of candidates mattered less. As we head into 2016, each party is quite unified on major policy issues — and these unified positions are very far from each other. The huge, substantive gulf between the parties will be reflected in the policy positions of whomever they nominate, and will almost surely be reflected in the actual policies adopted by whoever wins.When it comes to domestic policy I largely agree with this. There are of course differences in detail that can end up mattering; for example, I know Democrats who think Obama made a big mistake by focusing on health care reform instead of "cap and trade" or some other measure to fight climate change. But on the whole Krugman is right that for domestic policy the difference that matters is the one between the parties.
When it comes to foreign policy, I think he is wrong. On foreign policy the difference between Rand Paul and Marco Rubio is much bigger than the difference between Rubio and Hillary. And that's just their positions; in foreign affairs the president often has to respond to crises that were not anticipated in the position papers. Anybody who thinks the personality of the president never matters should reread the narrative of the Bay of Pigs crisis, when the Kennedy brothers stood pretty much alone on the Security Council for peace and diplomacy; a Johnson administration would have gone to war with Cuba. A Hillary administration would probably have dragged us into the Syrian civil war.
When it comes to the presidency, there are also issues at stake beyond the merely political. The election of a black president was important in and of itself, quite apart from anything Obama has done. The election of Hillary would also, I think, be important in and of itself. Not only would we have our first female president, we would also have the first administration in which the inner circle of power was mostly women -- Hillary has a lot of female friends and she can be expected to stock both the cabinet and the White House with women. This would change something about the country and its expectations that equal opportunity laws have not. Sometimes, symbols matter a lot.
So, yeah, the campaign is a wearying slog through the trite and the absurd. But politics is more than policy; it is the public conversation of the nation. I wish it were a more diverse and interesting conversation, but it seems to be the best we can do, so we might as well listen in.