Ask around, and you’ll find a surprising number of people have a smart speaker in their homes. As of January, 1 in 6 Americans own a voice-activated speaker, but Gartner predicts 75 percent of U.S. households will have one by 2020. With a broad gamut of capabilities—streaming news and music, answering questions, issuing reminders, and controlling connected home products—they can offer a good value proposition, particularly when paired with an attractive price point. But just because our Echos, Google Homes, and HomePods can do all sorts of things doesn’t mean we’re taking advantage of every single one of their features....