Good piece on the evolution of Wall St. bonuses over the past 30 years:
I am personally against directly regulating bonuses - it never turns out well when you try to interfere with market pricing. But you could simultaneously reduce bonus payouts and make firms less "too big too fail" by simply increasing the amount of cash/collateral trading firms have to maintain (i.e. reducing their leverage). You could even scale it based on the size of the firm, thereby encouraging smaller firms (which would in turn reduce the size of the average payout).
Or, you could just raise taxes on the wealthy. However, given the GOP's control, I doubt we're going to see that happen any time soon.