"the public generally seems indifferent to the issue or unwilling to rehash the bitter prewar debate over the reasons for the war."
If I recall correctly, both the UK government and the US Senate conducted official investigations of this topic last year
http://www.heritage.org/Research/HomelandDefense/wm534.cfm.
In both cases the allegations that the national executives had manipulated intelligence were disproved. I believe that the British investigation was pretty pointed against the source, perhaps someone can fill in the details.
Here is a summary of the US version:
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It is worth reading all 511 pages of the Report on the U.S. Intelligence Community’s Prewar Intelligence Assessments on Iraq—both for what is said and what is left unsaid. Both have a lot to tell us about how to make America safer. The Senate Intelligence Committee’s report makes the case for responsible intelligence reform and offers no evidence that political influence was brought to bear in shaping analysis to support particular policies. On the other hand, the report largely ignores the strategic challenges presented by the Iraqi regime and does not consider how the Select Intelligence Committee fulfilled its own oversight responsibilities in the months preceding the war in Iraq.
"If I recall correctly, both the UK government and the US Senate conducted official investigations of this topic last year"
The UK investigation that you're refering to was the Butler Report. The terms of reference were set by the government and specifically did not include an investigation on whether the reasons for war were justified. Essentially it was a review of the WMD intelligence and the processes involved in collecting and presenting it. It was pretty damning against the UK intelligence processes and the government in terms of how they approached these.
The Butler Report can be found online if you're really interested.