Why? We did/are doing the right thing in Iraq. WMD programs were discovered. Besides the fact that there were reasons cited beyond WMD, the WMD programs in the hands of SH alone was justification for regime change in Iraq.
There was and is a credibility hit due to this. Them's the breaks. There is nothing to hang our head over.
I think Kay's resignation is likely to hurt the President, as Kay was no boy of Blitz. I could be wrong, and I hope that I am.