Having an open honest conversation in public stops people second guessing - the problem is timing the switch from secrecy to openness. The markets are currently overly sensitive to honesty. Hypothetically, the markets would adjust to whatever new speed at which the information would become available, if the markets smell a bargain or money to be made they will go for it. If the mad Mr Market is too dangerous to be told the truth he'll have to be put in handcuffs to some extent.
If people were rationel beings maybe you'd be right - but they aren't. A famous Harvard Business Review study actually showed that only economiste and pshychopaths (!) could be shown to be consistently rational. Normal people second-guess everyone and everything all the time, no matter how much information they have.
Bubbles, panics, and all that stuff shouldn't happen but it does because people aren't rational. They're driven by emootions such as love, hate and in this case fear. You can be certain that if documents were released tomorrow showing that the IMF were preparing a Greek default there would be widespread panic.
Well, that's democracy for you. Maybe if honesty wasn't so rare, we'd have the populace acting in concert with their representatives because they have the same information. It's may just be the secrets that exacerbate irrationality. Google "open-book management" for more in this direction.
Furthermore, why is this "irrationality of the masses" more harmful than a leader keeping the secret that the country is asking about a loan from an organization that charges 50+% annual interest? After all, it's truly a rare thing that it's an economist who makes the final decision whether to go through with something like this or not. They're made by people receiving guidance from the economists you advocate secrecy toward those who pay their salaries. Why can't we all receive that guidance and information when it comes to matters of national concern?
