Their system of banks AND borrowers sharing profits and losses would have had a dampening effect on the excess by the banks over the last several years. If the banks were to suffer the losses as well as the gains, they would have had a more prudent approach to lending practices.
Also, if the bank actually owned the property and the borrower "rented" until the loan was repaid, banks would not have let the property bubble develop. A form of self regulation!!!!
Then again, look at Dubai, what the heck. Is there any system that could control man's ability to eventually wreck their environment. The smarter we get the more dangerous we get.