That's because chemistry is bounded by math and physics while economics is bounded by politics and fashion. Piketty made the point in Capital that only Americans consider economics to be a hard science; in Europe it's considered more like sociology or anthropology and pretty much absolutely nothing like, say, statistics. You also have to keep in mind that there will always be a market for "the sky is falling" narratives. On the other hand, "things are pretty okay" stories not only don't get sold, they don't even get read.
Yes, they call economics the 'dismal science' for a reason. It's necessarily full of psychology, speculation, and curve-fitting. At best, I think one can look at deviations from historical means, and then try to conclude if the cause for the deviation is long-lasting or not. It is a fairly popular view that monetary policies enacted to fight the last large recession fueled equity and asset bubbles, without the intended effect upon inflation, at least up to this point.
The problem is that for any economic model, you start by excluding data that doesn't fit your parameters - like Piketty arguing that the past 60 years are anomalous because of global warfare and therefore we need to pay closer attention to the 1850s or Goodhart et. al. arguing that the past 60 years are the only thing that matters because China and Collapse of the USSR therefore PIketty is full of shit.
Agreed. Of course, you can say something about the mean 10 year treasury rate over a given amount of time, but even in such a straight forward measure, whether or not the same rate at a different time has similar effects is anyone's guess. I guess the question is: Is the question worth asking? It's kind of like philosophical debate. Rarely is anything settled, but the process seems to have some value.