Culprits?

When a crisis of this magnitude hits, there is the natural human tendency to look for culprits. I tend to look at systemic issues that caused humans to behave in a particular way. There are a few "irregularities" that stick out:

1. Everybody in this system (from Lehman Brothers to Fannie Mae) depended on computer simulations to predict default rates. It is obvious now that the data on which these models depended were not exactly applicable in 2007 and 2008. Historical data always depends on context and that conext-dependency limits the usefulness of projections based on those data.
2. Why did AIG keep all the CDS transactions off the books? Was there malfeasance or were they just clueless? There is a big push afoot to regulate CDSs and create exchanges to trade them. Will that solve the problem?
3. Another big issue is highlighted here: "This ability to buy insurance on things that you have no insurable interest in transformed this [CDS] market into a huge casino." 'Insurable interest' in this case means buying insurance even if you do not own the underlying bond. As an example, you are prohibited from doing this with life insurance. You, dear reader, cannot buy a life insurance policy on my life. It creates too many conflicts of interest! Think mafia...
4. Mortgage brokers were the agents that built the shaky foundations of this mess. There certainly was some outright fraud. But there were also global forces at work compelling these brokers to commit fraud. After all, humans have been committing fraud throughout our not-so-illustrious history. Why should this particular instance matter so much?