Both Steven Kurutz’s “American Flannel” and Rachel Slade’s “Making It in America” follow entrepreneurs who have dared to produce American-made apparel at a moment when the domestic supply chains for such products barely exist. Both books are interesting to read. The human stories are moving, the founders’ determination admirable. But neither book finally provides a convincing answer to a question that lurks in the background: Should we even want apparel manufacturing to rebound in the U.S.?