The first reason is for the lovely, light mint syrup that permeates the fruit in this combination. Another reason to fashion your own fruit salad is to be able to pick out just those fruits that you and your family like. Use different kinds of melon here, or different berries, or fresh pineapple, or mango, or oranges. If you grow your own fresh mint, you know how easily it can spread. If, on the other hand, you need to buy fresh mint, keep it in the refrigerator in a glass of water lightly covered with a plastic bag.
Fresh mint is wonderful in iced tea, lemonade, and in certain Middle Eastern salads, like tabbouleh.