One lesson that some future government should take away from this term is the scope of Executive authority. It is historically ill-defined, other than it can neither make or override legislation. Some power is obviously going to rest with the Executive, but in some cases, Congress has devolved its authority to the Executive over the years, out of expediency or for whatever reason. It probably seemed safe, and made the government's reaction to quickly evolving events more responsive - until now.
Of course, much like reining in the power of the PMO up here, it will never happen.