Making labor less expensive helps firms hire people.
Tax increases appear to have a very large sustained and highly significant negative impact on output. Since most of our exogenous tax changes are in fact reductions, the more intuitive way to express this result is that tax cuts have very large and persistent positive output effects
As an economic historian, I appreciate what manufacturing has contributed to the United States. It was the engine of growth that allowed us to win two world wars and provided millions of families with a ticket to the middle class. But public policy needs to go beyond sentiment and history.
The stock market crash in October 1929 didn't destroy a particularly large amount of wealth or make people highly pessimistic. Rather, it made companies and consumers very unsure about future income, and so led them to stop spending as they waited for more information.
If increasing income equality is the goal, it might be wiser to put money into infrastructure than to subsidize manufacturing. Construction also pays good wages, but with lower educational requirements. And America's infrastructure needs are enormous.