Libertarians already understand the negative consequences of aggression, and pacifists understand the negative consequences of even lawful violence against other human beings. But we can push it even further: For the average person's goals, hostility against others can be quite counterproductive, even if "justified" by some ethical standard.
For example, a lot of people are pointing out that we're now seeing Obama's "true colors" come out, and that all of his early rhetoric about a different kind of politics, was just a lie. Well, yes and no. I think it is entirely possible that Obama really would have continued to sound so fresh and different, but he (thought) he had to adopt a different stance because of the incredible tactics employed by the Clinton campaign.
By the same token, the unimaginable scope of investigations into his and his family's background, and the rumors etc. that will be employed by supporters of McCain, will embitter him and his advisers. He will be much more receptive when his aides tell him to not bargain with the dastardly Republicans on taxes or health care, because "they can't be trusted."
We can push the analysis back even further. Given how horrible presidential campaigns have become, what kind of person even contemplates running for the spot? Only someone who (a) believes he has nothing embarrassing in his past, (b) is willing to endure public humiliation and scrutiny because s/he so desperately desires power, and/or (c) genuinely believes s/he has the answers to make the world a better place, and so is willing to endure these trials.
Generally speaking, I don't want someone matching any of those traits in power. It would be better if presidents were chosen randomly.
So yes, the Republican detractors of Obama will be "correct" in much of their character attacks (though not all; I'm still waiting for the alleged video of Michelle talking about "whitey"), but it's like giving ever harsher penalties for drug dealers: You won't stamp out the problem (in this case, awful Democratic candidates), and in fact just ensure that the survivors in the new equilibrium are even worse, by your own standards.