AS said many many many times, people who make the bank a profit, get bonuses, if they didn't they wouldn't take jobs there, nor would any good bankers, meaning those they did employ would likely be worse, make worse decisions and make less money, or larger losses.
Remember not all banks and not all bankers made a loss in the economic crisis(ruddy hell, its hard not to type Crysis these days

). Remember a bank could loss 40billion while the investment arm of the bank make a 10 billion profit, if you deny the billion in bonuses and all the good bankers leave, the next year the bank could make a 60billion loss with the investment arm making a 10billion loss but no one pays out 1billion in bonuses.
Is it worth saving 1 billion in bonuses, to loss 10 billion in profits? No, its not, its cutting off your nose to spite your face.
ITs "labour" thinking, they lie to everyone telling you how evil the big greedy rich people are, while throwing away business, profit, money, taxes and jobs.
Its the same way Labour over tax the rich, take say a footballer as an example. He can get 100k a week here, and used to pay 40k in taxes, and say he could work in Spain and pay 40k a week in taxes also. You raise the tax to 50% and in theory you're increasing tax income by 10k a week, great, but because that footballer is now making less money, he's MORE likely to move to Spain, which means rather than gaining 10k in tax a week, we actually lose his 40k a week when he goes to Spain, and Spain by not being greedy, gain 40k a week in taxes by charging LESS tax and encouraging the footballer to move there.
Lower taxes ENCOURAGE more jobs, and business and profit which INCREASES tax income, its the same anywhere you look, denying bonuses, and increasing taxes has for decades now decreased jobs, sent businesses packing to other cheaper countries, and decreased tax income.
Bankers deserve their bonuses, not least because the banks employed this people with bonuses in their contracts.
Now should banks be more careful with bonuses, should the contracts be more specific about what triggers the bonuses, should people not get them if they suck balls and lose a lot of money, yes. Should bonuses be removed, no, you'd just be losing billions in the long run for a VERY VERY short term very very small gain.