Apart from a possible arms cache and cash stocks this is what I have thought from the beginning was prize enough to carry out the assault...
Sacking of Benghazi consulate a catastrophic intelligence loss
Yes, the "attack" on the "consulate" was a well-scripted feint, except they didn't expect Woods to show up and start killing jihadis. The firefight got out of hand, a fire started, and poor Stevens, locked in his jail cell/"secure room" suffocated.
I'm sure this caused some consternation among enemy commanders, since they must have expected the same thing Woods and Doherty expected - air assault followed by rescue forces.
But they were well-drilled and their objective - the "warehouse" - was obviously very important.