When I looked at the chart, that was the first thing that entered my head when I saw the last bar "Middle class people" -- what about the poor. According to RW ideology, it was government forcing the banks to lend to poor people, and poor people avariciously grabbing on to any deal offered, that crashed the economy. In my message board wars, I have to deal with that over and over again. And like you say, that viewpoint isn't restricted to Republicans.
My own view of the financial crisis is that (after reading "Reckless Endangerment" and "Financial Shock" is that mandates requiring Fannie and Freddie to have 50% of the mortgages they buy be for low- and moderate-income households was part of the problem, and certainly helped it get started (the deterioration in lending standards) but that in the last 5 years or so of the bubble it went way way beyond that where banks and mortgage brokers originated loans without caring about the ability of the borrower to repay, because they could and did sell it to Wall Street firms that bundled them into various forms of mortgage-backed securities and then sold those to investors. If those investors got screwed later on, well too bad, all that mattered to the banks and the Wall Street firms was the big fees they collected originating and packaging these mortgages.