I was initially annoyed by the President's response, but then I considered his perspective. He cannot address this issue seriously due to still-popular opinion in the U.S.
Most people are not willing to think outside the box regarding the economy, and are especially not willing to openly re-visit their moral stance on drugs. It was actually pretty smart (and diabolical) of the President to address the issue the way he did, although definitely disingenuous. If and when legalization happens, the White House will not likely demonstrate loud support and I can't really blame them for that.
But look at the bright side... I think most people would agree that marijuana's overall reputation has been improving for a while. The fact that our President even discusses marijuana openly and in a light-hearted fashion helps combat negative connotations.