Why do we need Ants? Is it useful to humans, to the society?
Yes, ofcourse, you don't need to be an biologist to understand the need of an Ant.
Many refer Ant or Ant Colony to symbolize hard workers etc. Lets move away from aphorism for now and see the practical use, it doesn't yield anything like Cows etc, but they play an essential role in keeping the environment in balance, they decompose waste materials and recycle things back to Nature or Soil, in simple words they are our free Scavengers!
So each individual creature in this world has a role to play, whats is your purpose?