One thing conservatives tend to grasp better than liberals is the basic point that Barack Obama is a historically significant figure. Jodi Kantor's great piece on Obama's sit-downs with a group of presidential historians reveals that his admirers tend to have an oddly myopic view of this:
The historians have not seen Mr. Obama as a group since that final dinner; they figured he was too busy with his re-election campaign. When they discuss his presidency now, they credit him with winding down two wars and passing health care legislation, among other measures. Still, most of their reviews say that he did not come close to fulfilling his original aspirations: “nothing to be ashamed of,” “couldn’t put principles into practice,” “not transformative with a capital T.”
People will look back and say that the American social welfare state had three primary architects—Franklin Roosevelt, Lyndon Johnson, and Barack Obama. That's pretty transformative. They'll also say that Obama's eight years in office basically drove a stake in the heart of formal government discrimination against same-sex couples. There's also a grab bag of mid-sized initiatives in the stimulus plus a financial regulation bill, and he may even pass a law or two in his second term. Depending on what happens, we may also get a substantial shift in the judiciary.
Now "transformative" doesn't preclude "massive failures." FDR left the edifice of white supremacy in the United States basically unscathed, even though in retrospect we see the beginning of American racial realignment in his era. By the same token, there's a healthy chance Obama will basically fail to dent America's greenhouse gas emissions despite a quiver full of promising smaller green programs. But even if that comes to pass, the Affordable Care Act and the rising tide of gay equality are a really big deal especially in the context of broader public sector reform and demographic shifts.