The normal criticism of Palestinian violence is moral. That is as it should be, and Obama does not slight that: "That is not how moral authority is claimed; that is how it is surrendered." But that criticism leaves open the possibility of framing the debate over Palestinian violence as one of principle versus effectiveness. As long as it is framed that way, one can understand (though not agree with) Palestinians who say: you'd think differently if you didn't have a state; if it was your land that was constantly being seized, and your pregnant wife who had to wait for hours at a checkpoint to see a doctor. You'd put aside your principles and do what works.
That's why it's immensely important to say, clearly, that violence is not just wrong, but ineffective. This has always seemed clear to me: of all the ways to try to achieve Palestinian statehood, why on earth would you pick violence, where the difference between Israeli and Palestinian strength is greatest? And why would you not begin to wonder, after decades of violence with nothing to show for it besides blood and bitterness, whether some other approach might be better?
People who shoot rockets at sleeping children and blow up old women on busses are heroes in parts of the Arab world. Obama is directly challenging their courage. He is calling them out, and asking: what's so heroic about that? How does that show how powerful you are?
He's casting violence as a form of weakness. Again, that is both true and very powerful. And it badly needed saying.