I also don't think solutions/tools should be discarded because they are not perfect.
From your examples, it seems like your knock against prediction markets are the fact the aggregated predictions don't end being correct at times? Of course that's going to happen, and I don't necessary see instances of the wrong aggregated predictions of a market as a bug, but a feature. Human populations are wrong about things all the time in the aggregate. What better way to get better at decision-making than getting feedback on how we are wrong?
My argument for prediction markets was not for generating knowledge in the aggregate from all of the individual users' predictions. It was centered on the individual front as a way to reward individuals who are better able to predict the future. The uber context in which I was commenting was around who should be considered an expert. Prediction markets are one potential tool (albeit not perfect) to measure individual's conception of current reality and future reality.