It's frequently defended as a symbol of cultural identity, which helps groups distinguish themselves from other groups. It's a matter of pride. There are far more than most of us realize. Presently more than 6000 tongues being spoken around the world. Linguistics continue to search, however for distant relationships which may perhaps indicate all languages evolved from a single tongue.
Languages vary in importance.
Importance can mean the number of people who speak a particular language. More than half of the people on Earth speaks just eight languages. Therefore, the linguistic diversity of the Earth is shrinking. It's estimated that in pre-history humans spoke 10,000 and 15,000 languages. It's estimated that in 100 years there will be only 600 of the current 6000 languages still in use.