Lol, our big brains developed long after we left our jungle environment, and are fueled above all by protein (meat, so hunting). Our taste buds love sugar because fructose is a drug that plants evolved to get our ancestors working as seed dispersal machines. And I believe if you eat grapes or oranges or apples, the juice (and fructose) is barely wrapped in fibre if at all. Chewing an orange, you have extracted the fructose almost entirely. Do you think the "nutrients, vitamins, antioxidants" slow down the digestion process?