CRA was designed to have banks invest in the normal people of their community. So if a bank was in a lower or middle class community, the bank was requested to invest with those constituencies. CRA was not designed to lower standards for loans. In fact, sub-prime was not a goal of CRA. This is one of the big lies of the housing bubble. CRA could make accommodations by removing non-financial biases against lower income borrowers. But CRA never said to lower financial standards.
You can read more here:
http://en.wikipedia.org/wiki/Community_Reinvestment_Act
The housing bubble was fueled much more by rescinding the Glass-Steigall Act firewalls. This allowed local and commercial banks to act as investment banks, and allowed investment banks to get sucked into one of the biggest Wall Street scams ever, mortgage backed securities.
When you looked at the mortgage failures in California, Nevada, Arizona, and Florida in 2006 and 2007, which triggered everything, the vast majority of the "bad" mortgages were non-conforming (meaning nothing to do with CRA loans) or sub-prime (meaning extremely under-represented in CRA loans).
Later, as the problem spread everywhere, there was collateral damage all over the place, including some CRA loans. But again, these loans were under-represented in large part because loan standards weren't compromised. As a confirmation, the above article noted that at the bottom of the housing deflation, 55% of all commercial loans were underwater, despite the fact that commercial loans, by definition, had nothing to do with CRA,
The housing bubble was fueled by greed and speculation on both sides (buyers and sellers). But for lower income borrowers, CRA was never the cheapest (at least for the first year or two of your loan), easiest, or only mortgage available.
On the buy side, there were stupid people, there were speculators, and there were some crooks. But the crooks normally went for the big money (the non-conforming jumbo mortgages, especially those with zero down and no income verification).
On the sell side, every step of the sell chain was horribly greedy, but only on the non-conforming side that fed the Wall Street Mortgage backed securities. Wall Street was so desperate for more mortgages to repackage that they stop all the quality checks that FHA loans required. No one cared bout anything except getting loans that could be repackaged and dumped to pension funds around the world at great profit.
The sloppiness is a big reason why foreclosures are moving so slowly. Banks that originated the non-conforming mortgages still can't prove they ever owned the properties, or had the right to service them (that would have required proper paperwork, and when your in the midst of a scam who cares about costly proper paperwork).
CRA loans, on the other hand, had all the proper paperwork, and were much less likely to be sold by the originating bank (which viewed their local loans as safe and profitable).
When you look at why Canada's housing market didn't implode when the US market did, you need look no further than they never allowed non-conforming loans, and banks that originate a loan maintain some responsibility through the life of the loan.