“The campaign database would be important because it can provide a “human map” of access to Obama, a database of social networking within the White House circle. The Russians or the Chinese will be looking for access to intel, influence, etc…” @Wretchard

Bingo. The nature of intelligence gathering is to behave like a vacuum, gathering in mass rather than discreetly. The goal is to present as comprehensive and accurate a picture of the target as possible (whatever that may happen to be at any given time). The only limitation is in the ability to process, store, analyze, and comprehend the pieces to construct a whole. The answer to who did it and what were they after is “a large, sophisticated intelligence net”, and “everything and anything”. One email between two principles established a relationship. Every single email from Obama or one of his aids tells a lot even if only the header (i.e. from, to, date/time, and IP address) was available. It’s the same goal that NSA has, and why signal gathering and analysis on a volume scale is so successful. 1000 intrusions to small, inconsequential databases and data stores of federal, state, and local entities can be as valuable and the one big hit at Los Alamos, or other secure installations, given that the resources and IT apps and infrastructure is available to process the data.

From a Counter Intel perspective, the invasion tells a lot about the invader, maybe more than the invader might learn from the specific intrusion. It means that the source has vast resources invested in ELINT, HAS the resources to process and make sense of that volume of data, and has the will to penetrate official US systems “dirty”, leaving footprints all over the furniture on the way out.