Firstly, to reiterate a point made by Jeff Friedman:
A study by Rüdiger Fahlenbrach and René Stulz  showed that banks with CEOs who held a lot of stock in the bank did worse than banks with CEOs who held less stock, suggesting that the bankers were simply ignorant of the risks their institutions were taking.
So all this talk about bonuses has the potential to be plain wrong. Maybe bonuses weren't the problem. In fact, maybe it wasn't primarily an incentive problem, but one of ignorance. Even The Economist is on to this:
Far from expertly manipulating their firms’ books, many could not understand them.
There's a really simple point here that no one seems to be grasping: the main cause of the credit crunch was the fact that we're not omniscient. Not bankers, and not regulators. And like it or not, a policy-solution is forced to assume that we are.