1. It further established the already existing caste system. With the belief of being born in their caste is because of committing bad deeds in one's previous life.
2. Supporting the first point, Hinduism's belief of karma also puts forward that anything you do whether good or bad, will come back to you. This makes people conscious of their actions.
3. Another one is that it teaches to respect all living, believing everything is God's children. (rats, cows, and the likes)