In the case of international finance, I think it's really cool how an institution can help another institution raise capital, move debt, and mitigate losses. Like any system that involves independent actors, banking can (and usually is) diseased by those who are able (both intellectually and financially) to game it for their own gain and to the detriment of the system as a whole.
Banking, it seems, is almost aware of how self-destructive it is. These entities take on complex risks that the smartest people in the world can barely understand and they hope that everything will "just work" or, when things don't work, they rely on their overall value to the system - we can't let banks fail.
Still, I don't think all bankers are socially worthless. They help to create confidence in the banking system and in finance in general. It's only the "bad" bankers that are worthless, and even then they are only worthless to those who stand to lose if they fail.