Because there's not enough real world evidence on the matter that one can empirically observe, and we need stats and research?

manufacturing jobs [which] comprise just 10% of all employment in America (in percentage terms, there has been a virtually uninterrupted decline since 1970's 26%) (The economist)

Or: http://money.cnn.com/2016/03/29/news/economy/us-manufacturin...

And even those statistics can be and are manipulated in lots of ways from pundits to make a point that "it has never been better" and that everybody migrated happily to services jobs etc. That people used to be able to buy a house and send kids to college (and put some money aside) in the 50-60s with a manufacturing job, and they don't now is rarely mentioned. Or that tons of tricks are used to reduce the unemployment numbers.

Why, again, are manufacturing jobs the one type of job we're always supposed to be maximize, even relative to the pool of all other jobs? Is there more or less total employment, and does that matter less than manufacturing employment alone?

re: housing and college costs, I don't think that has much to do with manufacturing jobs in particular.

>Why, again, are manufacturing jobs the one type of job we're always supposed to be maximize, even relative to the pool of all other jobs?

Because the other major alternatives are

(a) service jobs that are a zero sum game of people inside the same country of circle-servicing one another,

(b) jobs like scientist, software developer, etc, that by their nature require few people so wont be increasing anytime soon either (and eliminate other jobs)

(c) UBI -- good luck with that.

I am not thoroughly convinced that non-physical labor jobs are zero sum, necessarily shrinking and/or reduce other employment. Why should I believe that? Can you cite any evidence to this effect?

Furthermore, if white collar jobs are "shrinking" means they should be irrelevant, manufacturing jobs are shrinking means they should be lamented?

Lastly, what if increasing automation means that manufacturing jobs will inevitably go away regardless of how anyone feels about it or complains about it? What do you propose to stop that? Manufacturing output of the US has consistently increased despite any variance in the amount of people it employs or the state of the rest of the economy.

>Lastly, what if increasing automation means that manufacturing jobs will inevitably go away regardless of how anyone feels about it or complains about it? What do you propose to stop that?

I propose a society where mankind DECIDES about what kind of jobs it wants to have (or none if they please so), and they are not dictated to it about the mere availability of some technology.