A funny thing happened when the smartphone took over all of our timekeeping needs: Men got really into watches. Aesthetics (as opposed to pure horological utility) became everything. Some guys went the über-macho route, strapping on pieces reminiscent of the wrist cannons Sylvester Stallone was fond of wearing in the '90s. Others went for pure blinged-out maximalism, which peaked around the time Beyoncé gave Jay-Z a $5 million icy Hublot for his 43rd birthday. But along the way, an undercurrent of enthusiasts sought to correct course with quieter, smaller vintage timepieces—and all of a sudden, the status-symbol watch shrank.