The lack of Sunni involvement in the Iraq government and/or in positions of influence, and effect, still seems to be the elephant in the Iraq room, and i'm surprised James Traub didn't mention it. Though that of his was basically on the Syria situation.
Yes, you've seen a couple of Nir Rosen's here on Tornado Alley. One from 2012
which in time past since has been shown to be spot on. In one of 2014 he gets a mention, this one on the GW Bush administration's Iraq fiasco ..
An Iraqi perspective: How America’s destruction of Iraqi society led to today’s chaos .. bit ..
Holland: A few years back, Nir Rosen wrote that an “obsession with sects informed the US approach to Iraq from day one of the occupation.” But how did this sectarian animosity emerge at the neighborhood level? Take me into a mixed neighborhood and tell me how the invasion caused people who used to be neighbors to turn against each other.
Jarrar: It started just by bringing up people’s sectarian divisions. I think making it a political identity was the first destructive force. And this happened right after the fall of Baghdad, when the US created the Iraqi Governing Council. The IGC was the first entity in Iraq’s contemporary history where people were selected based on their sectarian and ethnic identity. It had never before been the case that people were selected to serve because they were Sunni or Shiite or Kurdish. That brought it up to the surface. They started this quota system for political affiliations and then the ruling parties started playing on these divisions. http://investorshub.advfn.com/boards/read_msg.aspx?message_id=103665377
in which the GWB crowd not only planted seeds for the civil war in their de-Baathification policy, but also brought sectarian division to the fore to fertilize the seeds, as that bit makes clear. Hence, i'd say, the Obama administration's understanding as put in yours,
"Better to have a regime and a state than not to have a state"