I don't condone this hack, but morals/ethics aside for a moment: The one positive thing this hack has done is really give serious ammo to the battle for online privacy, because the demographic hit by this hack is the most politically & economically powerful demographic in the world....
What I find weirdest about the whole thing is the data wasn't sold back to Ashley Madison. The hacker(s) could have leaked 10 or 20 juicy names then probably cleared $10 million dollars or better. It would have been a bargain to Ashley Madison at that price.
HACKER: "Hello, I am an evil hacker. All your data is belong to me. Cough up $10 million or be destroyed."
ASHLEY MADISON MANAGEMENT: "Whatever, we don't believe you, go away."
HACKER: "All righty then." destroys them