I think you could also ask the opposite question about pretty much anything - why was this public? And I think the answer is the same - because I wanted it that way. Why should it need to be justified either way? If I want to keep something secret for a reason or by default or just on a whim, I should be able to, and if I want to make something public, I should be able to do that too. I don't think one choice is any better than the other as a default.