Our system is strictly based on confidence at this point. Fiat currency, fractional reserve banking, massive leverage, and more systemic debt than the world has ever seen all rely on the fact that big banks are essentially untouchable. We'll never see prosecutions of big banks or their principles. It would break the entire system.
If Obama had given execs the kind of treatment Larry Summers and the other half of his team wanted (heads on sticks to put it lightly) it would have rocked the investment world and brought much more pain to our economy than many could bear. The American people would have seen justice, but most likely at a substantial cost to the American way of life with ripple (tsunami?) effects seen and felt around the world.