A market is a distributed problem solving mechanism while a government bureaucrat is centralized problem solving mechanism.

In general you want a distributed problem solving mechanism since more people working to solve a problem is better then a small group of individuals trying to do it. This is why free-market based societies outcompete centralized command economies. So the phrase "let the market decide" isn't exactly that stupid of a phrase.

Now of course we want a market to have certain limitations on it to address the concerns you mentioned, but in general a relatively laissez-faire market is good for dynacism, growth, innovation, and producing higher quality products over time.