Good public policy is usually simple. Simple policy is not only easier to administer, but it's also more difficult to subvert. Consider a public option versus Obamacare.
Or an open securities exchange vs Dodd-Frank.
Democrats have become the victims of their own pusillanimity on these issues. The main Wall Street argument against these new rules is that they're excessive and onerously complicated. But they're only complicated because the Democrats didn't have the stones in the original Dodd-Frank debate to insist on simple concepts like putting all trades on open exchanges.
Instead, they built a system based upon a series of fiendishly complicated compromises. They keep adding more and more fine print to the infrastructural rules for things like Swap Execution Facilities and deriviatives clearing, and the more fine print there is, the more cracks and crevices Wall Street's lawyers can find to slither through.
"Pusillanimity" is an uncharacteristically generous bit of Taibbi mind-reading.