BLACK HAWK DOWN IS ENTERTAINMENT!!! NOT REALITY!!!
Actually, the movie pretty accurately portrays what you describe. Overly complex plan, underestimating the enemy, it's all in there. You call it a clusterfvck, the movie shows a clusterfvck.
Re: Cheering Somalis - This is described in the articles. I got the impression that they were cheering at the damage done to the Americans.
Re: Why we withdrew - When people saw our soldiers being dragged through the streets on the evening news, the question on most people's minds was not "Why aren't we kicking the sh*t out of them?" but "WTF are we doing in Somalia?" To judge it in the current context of 9-11, the War on Terrorism, etc. is a mistake. Additionally, if we had allowed what had started as a humanitarian mission to deteriorate into a slaughter, it would have made us look pretty bad in the eyes of the world. Look at Europe's reaction recently. How would they have reacted then?