I think this is interesting because this discomfort is very similar to that felt by those skeptical of evolution. Evolution is an unplanned system that nonetheless proceeds toward increasing complexity. There's no one in charge of it; the outcomes are determined by random copying errors and the environment in which these mutations occur. Life doesn't have a point (certainly not a grand cosmological or moral point) in evolutionary biology. It just is, and humans aren't any more important to the universe than any other creature. There is no central planner. Many people--almost entirely religious conservatives--are uncomfortable with this view. They see it as nihilistic and morally troubling.
Furthermore, I think it is fair to say that the skepticism of unplanned market systems tends to exist mainly on the left, while the skepticism of unplanned biological systems exists mostly on the right. This makes me wonder why that would be. Why aren't people on the left skeptical of evolution, too? Why is the right more comfortable with less regulation of markets? Granted, conservatives in the U.S. tend not to be very market friendly, especially in regards to drugs and prostitution, but I still think it is fair to say that conservatives are more friendly towards markets than those on the left.
Maybe I need to reread Rubin's Darwinian Politics.
One more point: Government--that institution that many would like to use to direct markets and reorder society--is also an unplanned system. It has no single mind coordinating it, and the outcomes it produces are not always what one would expect, and (in my opinion) they are seldom what one should find desirable. Government is a maze of competing interest groups, using votes, campaign contributions, promises of post-politics employment, lobbying, and even threats to push for their goals.
That's not to say that there are not market failures that a government could conceivably address; there certainly are. Rather, the question is whether a real-world government could reliably fix them without creating new problems. I'm much more skeptical about that. I would love to see payroll taxes replaced with pollution taxes; the potential welfare gains are enormous. I simply doubt that such a policy could make its way through Congress without becoming something terrible in the process.