because we've grown past that era
usa benefits much more from free trade- mercantilism is for developing countries
or as you note, isolated tariffs for specific reasons
what trump is doing just hits everything. any hope it will foster american manufacturing is greatly offset by the huge hit in trade. why? because old stupid assholes think the 1950s can come back?
furthermore, other countries grow stronger ties with each other
and our rivals
this is a gift to china