Exactly. US government politician's, bureaucrat's and employee crimes against US citizens and the Constitution are so numerous and disturbing that public knowledge would seriously damage the US government for decades, if not permanently.
This information is a huge source of leverage for anyone negotiating with the US government for anything, especially foreign nations. US government officials can be blackmailed into giving up most anything.
Putin is acting in Russian interests, not American, but that's his job.
Exactly! (I do, however, have a sense that Putin cares about America more than Obama does - but not because of this story). As you said, it's his job. Even if it were Israel or some other friendly nation to the US I think they would expect the same from the guy.