In conservative-land, you see, Obama’s first election was a fluke and his second a calamitous accident, both canceled by the ensuring midterms and both destined to be remembered as incidental interruptions of the Long March of Movement Conservatism towards total power. The idea that 2008 and 2012 are just as significant as 2010 and 2014 (maybe a bit more significant insofar as far more Americans participated) is outrageous to the Right, and so Obama mentioning them was the defiant act of a political nonentity.
Beyond that, the basic framing of Obama’s remarks on the economy left Republicans even deeper in the trap they’ve been in ever since conditions began improving. The main criticism available to them for the performance of the economy is the one Democrats (and Obama himself) have been articulated: sluggish wage growth and growing inequality. But Republicans have little or no agenda to deal with that beyond the usual engorge-the-job-creators stuff dressed up with attacks on the few corporate welfare accounts they’ve agreed to oppose, and then the Keystone XL Pipeline. On this last point, Obama was very clever in dismissing Keystone as one controversial infrastructure project we’re spending too much time fighting over as hundreds of others languish. It made Joni Ernst’s plodding Official Response sound all the more foolish for spending so much time on that one project.
Making the GOP look foolish is easy. Getting voters to show up and punish the fools in the GOP is the hard part.