Christ, nothing was hacked into or stolen - it was LEAKED. Wikileaks didn't need to steal it since it was GIVEN TO THEM by people wishing to LEAK the information. Those people in turn had it given to them or put in their responsibility.
Doesn't the whole idea of leaking imply that it was stolen information sorta? Like when somebody "leaks" a movie (WHICH PEOPLE GET ARRESTED/SUED FOR BY THE WAY) or videogame its considered theft. You say that like the people leaking the information have a right to leak it. it wasn't given to them or put into their responsibility meaning they could do whatever they want with it.
Also leaking military information is considered a crime labeled as SEDITION and you can get court-martialed and shit from it. So, yea, actually wikileaks is encouraging an environment of sedition.
As for transparency hurting a country I'm sure we can think of something :O
I'm sure there's been some stock market crashes/depressions caused by transparency which incited a panic in people.