Stinging nettles taste good. They have a long history of human consumption. They're in a family of plants (Urticaceae) containing no other common food crops, so they increase variety of diet, which to me seems like a good idea. The main drawback is the bad texture. The stinging hairs have an unpleasant furry texture even after you cook them (which stops them from stinging but does not remove them). This is why they're traditionally served blended or finely chopped in soups. If somebody could breed a version without the stinging hairs (not merely inactivating them) I think they would make a good commercial crop.