I think you're suffering from availability bias. You can easily picture polluted countryside or a population crash, whereas "undervalued currency or export dependency" sound like a minor point of abstract economics.

You may want to look at this article to get a feel for the extent to which Chinese urban policies are driven by a desire to project an image rather then any internal sensible policies. For example, people who aren't born residents aren't allowed to move into Shanghai or Beijing while a third of the newly constructed buildings remain empty.