[Disclaimer: Video temporary unavailable, it will be online soon again.] Without compassion the world as we know it would collapse. There would be only injustice, conflicts, poverty and discrimination.
Having sympathy is to understand what the other person is going through. Empathy is the ability to feel what the other person is experiencing as it were you in their place, and compassion is to take an active role supporting the one who is suffering hence the Latin word for it; Compati: co-suffering.