Apparently there is still at least one sane liberal left in the US.
The president's frustration, after delivering a sad series of similar speeches, is understandable. But his argument is still indefensible.
Even if you support "commonsense gun legislation" (as I do), there was nothing in Obama's speech that effectively argued for it. No policy proposals or serious justifications. No one listening to the speech would be persuaded to take a position he or she did not already hold. Obama was saying, in essence, that it is obvious what we should do about mass gun violence, that evil people are blocking it, and that they have innocent blood on their hands.
But it matters when the president of the United States decides that democratic persuasion is a fool's game. It encourages the kind of will-to-power politics we see on the left and right. In this view, opponents are evil -- entirely beyond the normal instruments of reason and good faith. So the only option is the collection and exercise of power.