So why is he such flippant and condescending?

Daniel Henninger at WSJ has the reasons for the "smart aleck" behavior.

JFK, an imperfect man, worked hard to stay perfect in public. So did FDR and Bill Clinton and Ronald Reagan. For Barack Obama to believe that any persona he offers the public will be OK with them is hubris. Showing voters a side of him that he enjoys, but many of them may not, is flirting with disaster. If all the positive vibe that held up his presidency on its first day ever breaks, the fall could be fast.