My man, if you think language is just a communication tool, you're very wrong.

Language is a carrier for centuries of cultural evolution. Russian language is rich with unique untranslatable slurs for neighboring nations. Why?

Language is a powerful colonization engine. Read history of any colonization. First thing colonizers do: teach colonized their language.

Once you impose your language on a person, you immediately integrate that person in your cultural domain.

I assume you just have no experience with the matter, and haven't seen this in action.

The language is literally pretext for the current war, if you read just a little bit about it.