The motivation (quite explicitly stated by Wolfowitz and other neocons) was to change Arab/Middle East political culture in a positive way. Whether McCain would have gone for that argument is hard to say. If he had gone for it, he would have listened to the military (it was actually called the Powell Doctrine) and sent 3x as many troops in the initial invasion, likely preventing most of the looting and perhaps preventing much of the insurgency. If the modest surge of 2007 rolled back the violence as much as it has, one would suspect a similar strategy at inception would have saved much in terms of $, lives and polarization of the Iraqi ethnic groups.
The roots of the financial crisis date back into the 1990's, and as with 9/11 there is plenty of blame to go around. But given other events of the past 8 years, no surprise Bush admin is going to take the hit for this one too.
We can only hope that Obama is really like Colin Powell. His rhetoric says he is, though his slender track record says otherwise.
