There is definitely a tricky balance to achieve between openness and also having the ability to have a meaningful conversation.

I was in that MP6 Skype conversation since the beginning (I committed the very first version of MP6), and while there is nothing there that couldn't be fully "open", the question of whether it should be or not isn't really the important thing. The important thing is the type of interaction involved.

See, you can't work with a thousand people at once. You just can't. The dangers of design-by-committee are well known, but there's also the issue of the number of voices in the room. If you have everybody talking at once, the conversation leads nowhere. Ultimately, somebody has to be in charge and making the decisions in such a large group and leadership becomes important, along with organization and everything else. But in a smaller group, say, 10-15 people, everybody can work together and at once without necessarily having well-defined structure or leadership roles. Smaller groups that are all on the same page can get things done quicker and faster.

I think that's the benefit of "private" conversations, they can be a smaller group of people, working towards a common goal. You get much more rapid iteration and active feedback. If everything had to be presented to a large group, then it would slow things down. Large group conversations take more time to gather and give feedback. Because of this, people in large group situations tend to work alone and only present final results to the larger group conversation, to avoid these time delays. It's a natural response, when you share with the world, you tend to polish the work more. But when you're sharing and working with just a few people, you can show half-baked ideas, thoughts, and concepts much more easily. Smaller groups tend to make progress faster because of this.

I guess what I'm saying is that group dynamics is a fascinating subject, really. :)