Well, while the employees were getting huge bonuses, the companies were hemorrhaging money and sinking the economy. Then, once they were propped up by the citizens(who gained little benefit from the bailout), they got more bonuses despite not deserving them. Also, because of the short-term focus of many banks, employees rolled in money while creating the mortgage crisis, that they never had to pay for. Hell, lots of Wall Street guys don't think they owe the public anything for saving their asses.
Also, executive pay rises no matter what they do because of peer-based pay. If RBS is paying their executives £20m per year, then HSBC has to pay theirs £20m to keep up. As does Northern Rock.
And the bonuses often come at the expense of other workers. A CEO, and other executives, getting a $10m bonus after laying off 1000 workers is pretty ridiculous.