I (sort of) agree that having many languages encourages diversity and coexistence of different cultures. However, I think that apparent drawbacks outweigh any potential benefits.
As a native Russian speaker, I know just how excruciating learning English can get. I have been learning it for 12 years, and most of the time it was no fun. For example, I once literally memorised 1500 words over a few months. Still, I cannot say that I speak as well as native speakers do. Most Russians never make it past learning to say "I don't speak English" with a funny accent. By the way, if you are an English speaker, you probably don't realise what it means not to know English. Let me assure you: it's horrible.
As a native Russian speaker, I know just how excruciating learning English can get. I have been learning it for 12 years, and most of the time it was no fun. For example, I once literally memorised 1500 words over a few months. Still, I cannot say that I speak as well as native speakers do. Most Russians never make it past learning to say "I don't speak English" with a funny accent. By the way, if you are an English speaker, you probably don't realise what it means not to know English. Let me assure you: it's horrible.