Because my ancestors in India knew that eating meat is not good for your body. Look at any health article, magazine or blog. Many of them promote largely vegetarianism.
My ancestors belonged to an advanced civilization, knowing the proper balance of food (protein, carbs, fat and other nutrients.) They had advanced agriculture, including storage of food, irrigation systems and farming, so that we could become vegetarians.
They and I care for all forms of life.
Primitive people live on basic instinct. Meat eating is a primitive instinct, passed for generations. When you become advanced and sophisticated, you can change the way you live.
Livestock cultivation generates the highest amount of gases contributing to global warming and harming the environment, according to the chief of the United Nations.
As far as I know, India is the only culture which promotes vegetarianism.