"After all, if Anonymous retrieved documents from an intelligence agency that should have unbeatable network security, what?s stopping criminal groups from doing the same."
Seriously doubt that Anon got these directly from NSA. Just like all gov't agencies (but most especially the NSA), they are "off-line". Anything sensitive (especially this data) is not on the internet, but only on an intranet, which means to get the data either 1) someone screwed up (purposefully or not) and put it on the internet or 2) someone had physical access to an intranet connected PC.
Given that they have regular snipers, dogs, squad cars, helicopters, and tanks around Ft. Meade/NSA, I doubt that physical access for an unauthorized person is plausible. Hell, even if you just make a wrong turn near NSA, expect a full interrogation on the side of the road while they run your personal information (I know - I drive by NSA everyday.... signs clearly say "Employees Only" but at least one-out-of-towner will take that ramp each day. Must really ruin there day to sit there for hours being questioned).