Why is chocolate generally sweet?
It's not. The original consumers of chocolate, the Native Americans, had their chocolate in bitter teas and savory moles. They mainly were after its caffeine effects. We could speculate about the overuse of sweeteners in general, especially among peoples of European descent. Other ingredients like mint, cinnamon, and cardamon come to mind. In the European culinary, those ingredients used extensively for puddings/desserts; in Africa and India, these are ingredients for savory stews. The fetishization of sugary desserts and exotic ingredients in Europe is partly to blame. Look up some traditional chocolate moles or consider adding it to a chili con carne recipe for a new way to enjoy chocolate with less sugar.