The most dangerous thing we could do to the global financial system is to go some way to reforming it.
Commentators are looking at what we have now - a manifestly unreformed system - and are crying out that if we don't do something a financial crisis along the lines of 2008 will happen again. However, whilst this wariness continues, the last thing that will happen is the same thing again, even the same sort of thing. People are expecting it, looking out for it and, at the first signs of it, will be all over it. Everyone is acutely aware of risk and exposures.
Moderate reform - on Walker Report lines - might be sufficient to persuade people to move on, to divert their attention, make them relax. But it would almost certainly be insufficient to rule out the possibility of a 2008-style financial crisis. This could well make a crisis more likely than it would be under current conditions.
The safest option would be to radically overhaul the global financial system - Glass-Steagall-type legislation, prohibitive capital allocations for risky trading activity, restrictions on derivatives, etc. - in order to make a 2008-style crisis impossible. However, the latter will prove politically and fiscally impossible.
So we have two just two realistic options: do a bit or do nothing. Better do nothing.