Nobody was twisting the banks arm to make sub-prime loans, they couldn't hand them out fast enough!
They weren't going to keep those loans, so they didn't really care. The loan officers were making money of setting them up, so they didn't care. The stock market would snap them up in a heartbeat, bundle them and sell them for a profit. AIG would insure them and everyone was happy! Keep the money flowing!
This was a systematic failure across the board. While one could make a case for the Gov insisting the banks make some sub-prime loans (a PERCENTAGE of their portfoilo), the banks were MORE THAN WILLING to play the game. When the Gov said 15%, the banks were like, "No problem, how about 50%?" The Gov was like, "OK". Freakin' cluster screw up all the way around.