FUZZY FLEECE jackets, an old standby of the Clif-Bar crowd, have made an abrupt leap from your local REI’s outdoor-gear offerings to the pricey heights of fashion. In 2018, big-ticket labels such as Balenciaga, Lanvin and Moncler produced fleece jackets with four-figure price tags while celebrities like Shia LaBeouf, Vampire Weekend’s Ezra Koenig and Kendall Jenner were all photographed in their own napped coats. And this trend has trickled down particularly swiftly. Today, a budget-conscious shopper can get a stylish $29.90 fleece from Uniqlo or a $50 plush bomber from Zara. “We’re seeing [fleece] across the board from...