Let's me think a bit.
Deep Throat: There was a conspiracy to commit a crime, and the agency in charge of investigating was covering up the crime. So Deep Throat went public with the information to let the public know that there was a crime committed.
Karl Rove (allegedly): Didn't like someone who was informing the public that the information the Administration was supplying the public was false, so he leaked information that had no clear purpose but to punish the person by destroying his wife's career.
Seems to be a difference to me. Maybe if Rove leaked the information because he felt the CIA was a criminal organization and so outing the criminals involved is in the public interest, then I would consider him a hero. But leaking information just to punish someone as part of a political vendetta doesn't seem all that heroic to me.