Humans need to loose the tribal mentality. They need to realise they really all are the same. They talk about "culture" and such but the truth is, those minute, completely socally constructed "differences" are that causes war and chaos. There needs to be a shift, to one single humanity with many individuals, not many groups.
Perhaps a mandatory lingua franca will help push humanity forward in evolution.
Of course it sounds like a great idea for people to all speak the same language. It might bring greater comprehension and sharing. However, it is never going to happen because people do not want to give up their own languages and cultures. And it might actually be a cultural detriment if this happened.
Each language is embedded in a culture. If a language is removed from a culture it takes away a cultural identifier. Take the Native Americans for instance. One of their cultural identifiers was their language. It was stripped from them, and they were forced to speak English, and forbidden to speak in their foreign tongue. This is now something they are trying to relearn and identify with to bring back their cultural roots. Integrating a universal language would be stealing identities.