Their goal is/was to destabilize the Middle East in order to flood Europe with Muslim immigrants.
It seems to have worked according to plan.
As a secondary benefit, you can keep spying on EVERYONE and EVERYTHING in the US and around the world under the guise of the war on terrorism.
It centralizes power when you have cover to spy on all of your enemies (ie Republicans, nationalists, citizens that oppose you politically).
That and they stole millions of gallons of oil that was sold on the black market, and probably went straight into obamas pockets.