In this case, the Secretary and Undersecretary of Defense wanted an investigation of intel to determine whether Iraq had operational ties to al-Qaeda, a reasonable question given the circumstances. The CIA -- which the Democrats believe got it wrong on WMD -- didn't believe that radical Islamists would cooperate with the supposedly secular Saddam Hussein. Donald Rumsfeld and Paul Wolfowitz authorized Feith to review the intelligence to see if evidence existed for a different conclusion, and Feith found enough contacts between Saddam and AQ to at least challenge the notion that they would have never considered a partnership.
In other words, the same CIA that failed to predict the collapse of the Warsaw Pact, the 1991 coup in the Soviet Union, Saddam's invasion of Kuwait, and 9/11, was supposed to be trusted by the DOD. I don't think so. If anything, Rumsfeld, Wolfowitz, Feith, and the others who were criticized by Democrats simply did their job.
There is always a benefit of getting a second opinion on things. Especially when one is dealing with a high-stakes situation. The Inspector General's report is nothing more than pandering to the Democratic Congress, which will be running with this to justify stabbing the troops in the back.