We are designed to eat meat. It is scientifically observable by the fact that we have some sharp teeth designed for tearing flesh. Also by the fact that we require B-12 which is most abundantly found in meat. Yes, we technically can survive without meat by using supplements, but they are more expensive than meat. An entirely vegan world would result in the death of every poor person. It would be foolish to allow our sympathy for animals to override our natural necessity for eating meat. Emotions cloud judgement. I agree that we could treat our farmed animals better for the sake of sympathy, but we would be risking our species by removing meat from our diets.