Exposing corruption is good! But, what wikileaks has done is something beyond exposing corruption.
For example, most statements in the recently exposed US embassy cables were already known but now we know them in writing. This exposure may have exposed some amount of corruption but it has exposed lots of details that has nothing to do with corruption. For example, opinions of US diplomats about foreign leaders. Exposure of such opinion can only cause difficulty in international relations and a great distraction form real corruption.
There are many aspects why this kind of exposure may cause more harm than good. I can think of following objections:
1) Potential backlash: US govt now has a genuine claim of attack on it. Now they can move in the direction of clamping down on internet, passing tougher espionage laws, and having no sympathy for whistleblowers. And, Govt. may gather lots of support from people for taking such steps. We may end up loosing the freedoms, we already have.
2) Lost focus on real corruption: Information of personal opinions of diplomats amuse people a lot. There were headlines about opinion of American ambassador about french president Sarkozy. While, news ignored involvement of Americans in many serious criminal actions. Now! Julian Assange’s safety is international concern. He is only a messenger and anyone can take his place.
3) Invasion of privacy People say things in private that has no factual substance. Just opening up all the US embassy cables is a huge invasion of privacy. It will harm many people’s reputation and future conduct of international relations. This is a harm caused by this leak. The question is how much value one should assign to this harmful effect of leak.
4) May be improvement in some cases but no change in process of corruption: Corruption is most often not just a particular act but a process. Officials get used to it. They do it as matter of daily business. Exposing corruption here and there is always good but it can not change this mindset of corruption. If one wants to root out corruption in some aspect of government then one needs to fight a long sustained political battle that may last generations. Many times there is no other option for politics.
I hope I am wrong! May wikileaks bring sea of change! Amen!