Repeating post 147 here, Article II makes the President the C-in-C. He can do as he pleases with the military. As FDR put it, "I cannot declare war, but I can wage war." I understand that, and so should any semi-literate congresscritter. The Constitution was written in a time when Congress met for only a few months out of the year, so I understand and support that function for the President.
The AUMF was therefore redundant and superfluous. It was an unnecessary statement, and its motivation was clearly political, so that the Global War On Terror could be prosecuted.
As the congress was passing that measure, it was also REFUSING to investigate the events of 11 September, and getting rid of the forensic evidence at WTC at almost light speed, in violation of intelligent investigation of the biggest attack on US soil in the history of the country. Similar behavior to its investigation of the Murrah Building event, but I digress.
So, why must a big show be made (AUMF) to give the President powers he already clearly possesses? To impress the gullible, is the correct answer. The gullible and the uninformed.
This is relevant to the thread topic because the AUMF is frequently brought up by those defending the illegal actions of Obama in killing the young man about which this thread was started.