Why Didn't Obama Deliver a Knockout Punch?

With a winning performance in Friday night's debate and a growing lead in national polls, one would think more political observers might start to appreciate what Barack Obama is on the verge of accomplishing. Maybe, just maybe, he knows something the rest of us don't.
Maureen Down is among those who wanted Barack Obama to have delivered a knockout blow at John McCain Friday night:

Given the past week, the debate should have been a cinch for Obama. But, just as in the primaries, he willfully refuses to accept what debates are about. It’s not a lecture hall; it’s a joust. It’s not how cerebral you are. It’s how visceral you are. You need memorable, sharp, forceful and witty lines.

Perhaps Dowd is thinking about the kind of lines she would deliver in a debate, but then she isn't running. James Fallows seems to understand better what Obama is up to.

Obama would have pleased his base better if he had fought back more harshly in those 90 minutes -- cutting McCain off, delivering a similarly harsh closing judgment, using comparably hostile body language, and in general acting more like a combative House of Commons debater. Those would have been effective tactics minute by minute.
But Obama either figured out, or instinctively understood, that the real battle was to make himself seem comfortable, reasonable, responsible, well-versed, and in all ways "safe" and non-outsiderish to the audience just making up its mind about him.

Keep in mind that even after weeks of erratic campaigning and widespread dismay over his pick of Sarah Palin, John McCain still enjoys a large measure of good will among voters. For years he has been lionized by the press and immensely popular among independent voters.
This reserve of good will can't be wiped away with a few spicy zingers. Even the most memorable put-down line in recent debate history—when Lloyd Bentsen told Dan Quayle, "You're no Jack Kennedy"—crystallized public opinion instead of turning it around. And by the way, the elder Bush still won that election. Perhaps Obama understands that the way to win is not to convince voters that John McCain is unfit to lead, but to present himself as someone they can support.
Another common complaint is to ask why Obama isn't further ahead in the polls, given the general political landscape. On this point it may be useful to recall that even Bill Clinton in 1996 failed to hit 50 percent; he won with 49.24 percent of the popular vote over Bob Dole and Ross Perot. The last Democrat to break 50 percent was Jimmy Carter in 1976, with 50.1 percent. Ten presidential elections have come and gone since Lyndon Johnson delivered the Democrat's last landslide victory. Barack Obama is lengthening his lead into six to seven point territory, which is far better than either Gore or Kerry were able to do at this stage of the campaign.