Er... Lighter? I think your broad outline will wind up (pun accidental) covering the next 100 or so threads.

A. It's all W's fault.
B. The US is capable, and willing (under the right direction--see 'A.') to do really stupid things just because we can.
   (1.) I believe the war in Iran is one of those things, and probably the war in Afghanistan. BUT I lack the intelligence (military info--stop laughing) to know for sure.
   (2.) I believe killing O/UBL is NOT one of those things. I think farting around and starting a bunch of wars instead of going after O/UBL IS one. (See 'A.')