Perspective on Obama admin actions re: Bush WH e-mail case?

According to this article, the new Obama Justice Department is also fighting a lawsuit to recover Bush era White House e-mails.

There may very well be some good legal reason for this, or precedent to prevent, but right now, Obama’s opponents are using this as a club: “Change, my ass!” “See? See? Bush wasn’t so bad! You liberals went insane when he tried this!” “Media bias! Media bias!”

So I thought I’d get some more information on this issue. What are the basic principles here? And which side is more “right”?