The hard economic reality
Banks borrow (as interest-bearing deposits) and lend them judiciously to make profits. That is their business. But, they realized that borrowing (not as deposits, but as loans) is a better way to reduce cost of capital. They borrowed, and they invested; in their quest to out-pace one another, banks invested borrowed money in risky business of speculation -- they provided 100% mortgages (or zero-down payment mortgages), they provided funding to unregulated hedge-funds.
Banking is a sensitive business. A bank's deposit risk is proportional to the risk of the bank's loans (investments). In the quest for increased profits, banks took undue risks by investing in unregulated instruments.
Governments have since realized that they cannot let banks with customer deposits fail. It is clear that money from retail banking should not be used to fund risky loans -- venture capital, hedge funds, zero down mortgages. The owner of the money must be aware of the risks that they take. Retail banks must also be prevented from investing in complex derivative instruments where risk assessment is complex, or even impossible. Banks must also provide customers with an option to deposit in safe custody deposits -- where banks do not invest capital, but keep it in safe custody.
The central banks must give its own ratings for banks based on its investment risk, and must be re-assessed and declared periodically. Banks must disseminate this information in customer bank statements prominently. It gives customers the required information to move their money into a central bank backed safe deposit, or move their money to another bank. It gives banks an incentive to be diligent in their investments.
Governments, on the other hand, rode the real estate inflation as if it was real growth. In reality, governments turned a blind eye to real estate inflation because it brought them revenues. They are supposed to act to temper undue upswings as they are acting now in a hard downswing. If they had acted during the upswing, there would have been far less pain.