
Whee! This is fun. Brian, here is why your concerns are misplaced:

See that tiny little uptick in the red line there? That's the thing that has everybody horrified. Meanwhile, Obama has since about April been consistently pulling 45-47% or so, which considering unallocated undecideds and a race with THREE prominent third-party candidates is clearly a winning percentage. Damn but Democrats scare easy.
To your specific points:
John McCain is a terrible candidate who is running a terrible campaign... Barack Obama, on the other hand, is the most exciting candidate the Democrats have ever had. So WHY IS HE ONLY WINNING BY TWO POINTS?!
Excitement about a candidate, and the quality of the campaign, will manifest itself almost entirely in election-day turnout and polls from the days immediately beforehand, as marginal base voters decide whether or not to bother voting. You can't measure that in August. Meanwhile, Obama's lead -- which has ranged in the past few months from about 2 to 7 -- reflects the structural advantages he has in this electorate very well. (I repeat: John McCain is not, in fact, winning.)
I disagree that people aren’t paying attention. This election is different from every other before it, and I think people are watching.
Be careful with your assumptions here. Yes, this election is different; but in order to know that, you have to have been paying attention already, and you have to be familiar with previous elections. That leaves out the huge and decisive portion of the American public that only follows politics with a passing interest, and which never pays attention before the conventions and Labor Day. It's quite likely that the politically-engaged population (like us, and all of our friends) is more excited and paying more attention than usual, but that doesn't matter, because we vote consistently. It's the disengaged, low-information marginal voters that matter.
But even if they’re not paying too much attention, every household in every swing state is currently getting bombarded with McCain’s attack ads. And while the ads may be completely freaking ridiculous, the problem is that they’re not being countered by the Obama campaign, and impressions are formed early and are hard to change.
Yes, there are a bunch of attack ads airing, but their main purpose right now isn't to reach marginal voters (who, I reiterate, don't give a damn this early) nearly as much as it is to define the media narrative which, in traditional campaigning, shapes the actual gameplay in September and October. Now, Obama's campaign is hardly traditional, and it's going to rely on a whole different voter universe (see: their startling voter registration efforts) than the one which is traditionally swayed by media, so I'm not too concerned about that.
I also reject the argument that the race is all about the electoral votes and the popular vote doesn’t matter.
I didn't say that. My point was that national polls aren't very indicative because they can't reflect Obama's weird impacts on turnout. Certainly a rising presidential tide lifts all downticket boats, and I expect that to happen much more dramatically than the polls can possibly represent.
...The thing to remember is that not only does Obama have a consistent lead, recent Chicken-Little-ism notwithstanding, but we can reasonably expect him to overperform that lead substantially on November 4. Feel better?