Remember when everyone was discussing how bad it is for the NSA to know everything, because they can do things like ride in at critical moments in someone's life, like a politician's, and blackmail them with releasing something unless it goes their way?

Same argument holds with China, or anybody who gets the data.

Plus, the ability of attackers is not bounded by your creativity or credulity, or mine. The question isn't whether you or I can come up with something interesting to do with the data, the question is whether anybody who gets their hands on it can.

For the most part, the data really is mundane and irrelevant, sure. I know some government employees I went to college with, none of whom are in any position to do anything all that interesting at China's behest. But it's that .1% percent of data on the movers and shakers, and the people who will be tomorrow's movers and shakers, that is very valuable.

(And I've got a bridge to sell you if you think the full range of the hacking has been revealed yet.)

Edit: Oh, hey, look what I found in my newsfeeds literally one minute later: http://www.wired.com/2015/06/opm-breach-security-privacy-deb... "Federal background checks, after all, are meant to suss out information that might be used by foreign enemies to blackmail a government staffer into turning over classified information. And that stolen information could be used for exactly that extortion purpose, says Chris Eng, a former NSA staffer and now VP of research at the security firm Veracode." They literally got their hands on the forms constructed to contain exactly the information we didn't want foreign governments could get.