The real damage of the drip, drip pelting on Barack Obama's head is not the tarnishing of his branding as a different type of politician. It's his weakness as he backpedals from every small blow.
In real time, it is showing that Obama doesn't have the street gritiness quotient we want in our commanders-in-chief. If he apologizes for something he didn't even do wrong, as Eric Zorn notes, how will he deal with an array of international leaders that include some cagey characters, to put it politely.
It may appear right now that there's isn't a sane Democrat in the country, as they all funnel to the left of the political spectrum like a golf ball on one of those Oakmont Country Club greens. However, a sizable number will snap out of their leftist haze when the primaries near. Democrats are mostly looney, but they weren't nuts enough to nominate Howard Dean four years ago. They are keeping their antennae pointed near enough to reality to make sure to nominate someone who won't be roadkill for a Republican on the issue of national security.
Notice how Hillary Clinton is slowing drifting ever so slightly to the right and will do so as long as she believes Obama and John Edwards are neutralized.
Some might hypothesize that Obama is showing strength by acknowledging "mistakes" by his campaign staff. That trait might play well with some of Oprah's audience but it won't play well with the security moms and dads out there who intuitively sense we better have someone who can dial up the Clint Eastwood stare when necessary.
If Obama wants to apologize, he ought to say it was a mistake to pledge that his campaign wouldn't dare point a reporter toward the sleaze that permeates the Clinton campaign. His current campaign posture is that of a man who remains busy trying to deflect his own boomerangs.