> Every time a language dies, like latin or summerian did, we gain uniformity
And that's not necessarily a good thing. It is not just a language that dies, but a part of the culture also dies with the language. I do get the appeal of the world having one language, but attaining it at the cost of diversity would be a _big_ price to pay.
I speak a southern Indian language called Malayalam (34 million speakers). There are some things that are simply untranslatable to English - these words/concepts are closely tied to the way we live. Now if everyone in my town starts speaking only English suddenly, it would definitely affect the way they think[1], function, and would inevitable change the culture. I am not claiming that change is bad, simply arguing that preserving a language might help preserve a culture.
[1] IIRC there's been some scientific literature on this. I'll look it up and edit this post when I get time