The only time 'too much' is leaked is when operational intelligence is released at a time when it can cause unnecessary deaths or operations failure.
In a democratic-republic, we elect representatives. These representatives take actions and order other actions to be taken. If we are kept unaware of what money is spent, where it is spent and why it is spent, then can we possibly evaluate our representatives? If we are unaware of actions that are taken, where and why, then can we ever be able to accurately say: my representative/president/whatever did a good job? Ignorance is never a good thing. Without knowledge we cannot make knowledgeable decisions. I don't know about you, but 'trust me' is not something I want to hear from people we have surrendered power to.