I recently watched a news feature that discussed the disappearing language of an obscure inuit tribe. The fear of that language going extinct made national news and I'm not entirely sure why.
I understand that people will argue that their language is part of their culture but that's like saying vision is part of your culture. We all need to see to get around, we need to communicate in order to function in a group... so exactly how is that at all specific to any culture... we all do it.
While the culture issue might be argued as a pro for retaining different languages there are many more cons. The inability for us to communicate with each other is a very detrimental issue. In order for us to work together on any issue it is essential that we be able to communicate.
So why not one language? Why not one common tongue?