One thing I find attract of anonymity is that a person can make statement without risking it being permanently associated with him for the rest of his life. He can test ideas, push boundaries, perhaps discover something about himself or his previous assumptions. We are only sharing information after all
If most anonymous speech were like The Federalist Papers then I would agree. I think the mean-value of anonymous speech is either zero or negative. I'm aware this is a feeling and not something I can prove.
