Risk is, probably, fundamentally, unfit for use on operations...
Simply having armoured vehicles is a form of risk treatment as otherwise the whole army would be equipped with stripped down landrovers.
An infantry commander does not send a foot patrol into an ambush as he is aware of the risk and takes the Avoid Risk route.
What I think people are struggling with here is we initially went into Iraq with a 'win the ground war, smile at grateful locals, sneer at the Americans, soft hats, help the Iraqis set up form of Government and home again by Christmas' sort of attitude.
Very similar to the current mess masquerading as an Army we have today, all decisions on the emerging insurgency and management of risks were made on the 'how many bods have we got what kit do we already have?'mindset.