Exactly, that's why different languages can spawn different communication. Certain things cannot be translated, whether they are idioms or grammatical constructions. It's not just "sad", it means a unifying and, in some case, simplification of thought. Now, with English becoming more dominant, I guess it depends on your background and ideas whether this reduction to "things that can be expressed in English" is a good thing or not. I pick English here, because it is the most obvious example given international trade, travel and the internet, though the same applies for various big, hegemonic languages in their surroundings, and the same happens with dialects even within a technically mono-lingual environment.
The cool thing about languages though is that they evolve. English is a prime example of this: things that can't be translated just end up being imported and becoming new English words.
The end result is a more powerful language, where you can express the combination of certain ideas and concepts that simply couldn't be expressed in a single language before.
On the other hand, I'm a monolingual English-speaker. I personally gain much and lose nothing in this scenario, I have no real conception of what it feels like for the hundreds of millions of people who do speak minority languages; so I'm not sure I'm qualified to judge.
You gain a great deal if you have the ability to communicate with millions (billions?) of people that you otherwise couldn't.
Being understood by most people (instead of almost none) is pretty handy.
Second, the whole world doesnt need to speak the same language for cohesive unification. We just need star trek level translation which doesnt seem so far fetched these days.
Finally, everything comes and goes- the stars, the tide, human life, and language. Have you tried speaking to someone from east Baltimore lately? I havent either, but according to my source, The Wire, they speak a language that would probably be close to unintelligible between people from other parts of the English speaking world.
In other words, I'm not worried about language diversity- whenever humans find the need to express themselves in ways that doesnt fit in the current framework, they find a way.
I think language is a clear representation of culture - your first language directly informs how you see the world.
The world would be a lesser place if everybody grew up with the same linguistic experience.
"""5 But the Lord came down to see the city and the tower the people were building. 6 The Lord said, “If as one people speaking the same language they have begun to do this, then nothing they plan to do will be impossible for them. 7 Come, let us go down and confuse their language so they will not understand each other.”
8 So the Lord scattered them from there over all the earth, and they stopped building the city. 9 That is why it was called Babel[c]—because there the Lord confused the language of the whole world. From there the Lord scattered them over the face of the whole earth."""