The links helped, thanks! The second point not so much, as neither gov. debt nor the aging population is anything new for Japan. In past crisis the Yen even rose. So I doubt that those two issues suddenly eroded trust.

I already accepted this answer, but just realized that I actually do not completely follow. Would $\eta_1$ not be interpretable as causal under the conditional mean independence assumption? And why would regressing Y on an exogenous X (and endogenous Ws) yield an inconsistent estimator for $\beta$? From my understanding it would only be a problem if the Ws where not included and are correlated with X and Y.

Thanks, for a great answer! But is there an advantage in running the regs on the aggregate level to running them on the county-industry level, if I cluster on the state level in both cases?

Ok, that makes sense. I will change the question.

Maybe I did not express this well, I am in no way putting micro over macro theory in this question. Also I know that one can use quasi experimental methods for macroeconomic issues. I am only talking about time series econometrics vs. the quasi experimental stuff. I also know the DiD paper, but I think since 2004 a lot has gotten better (of course nothing is ever good enough though). Lastly, I think the advantage of the quasi exp. methods is that weaknesses can be revealed quite easily, e.g. a good paper will show and discuss how weak/strong an instrument is.