I always thought the answer was obvious. This has come up so many times in last few conversations that I think its time to blog.
Open Data is for Governments. Because they have always been closed and they have all the power (money, muscle power, access to resources, ability to change or manipulate law) and its a deadly combination just enough to kill democracy. So its important to know whats going on.
Privacy is for citizen. They are weak when compared to Governments. Most Governments (or corporations) have enough information about them already. We need legal and social frameworks to protect ourselves from them.
To balance the power we need more openness from governments and more privacy to citizen.