This is extremely perceptive:

This is my unscientific opinion, but I think that the main reason that Obama isn't as far ahead as all of us Good-Minded Liberals think he should be is that the race has, so far, only been about Obama.

Even though Generic Republican gets blown out by Generic Democrat, and McCain's policies get thrashed by Obama's policies, neither is really accurate in describing the race right now. Specificity has a way of bringing a candidate down, and gives the voting public something to be against.

Let's say that (grossly), the Republican Brand stands for "Patriotism, Small Government, and Family Values" while the Democratic Brand is "International Cooperation, the Environment, and Civil Liberties." (I know these are silly in their over-simplicity, but just bear with me.) Let's also say that candidate McCain has specific policy proposals that are "Stay in Iraq, No National Health Care, and Don't Meet with Foreign Enemies" that contrast with Obama's "Get Out of Iraq, Mostly Universal Healthcare and Meet with Enemies of the US." The generic Democratic brand beats the generic Republican, and the specific Obama beats the specific McCain. Unfortunately, because the media is focused on Obama so much, the race isn't Republican vs. Democrat or McCain vs. Obama, but rather Republican vs. Obama. "Patriotism, Small Government, and Family Values" vs. "Get Out of Iraq, Mostly Universal Healthcard and Meet with Enemies of the US" is a muuuch closer race to call.

I wouldn't worry. Once the public focuses on both candidates' actual policy prescriptions (instead of just Obama's...*coughMEDIAcough*), I believe that Obama's lead will grow.