You're right of course, and this is precisely why preserving languages is important. They are loaded with knowledge, and passing around this knowledge is time consuming, hard, or sometimes unfeasible if not enough speakers still live :)
I'm not comfortable with the idea that something which pops into my head today represents a burden for future generations to preserve, who will have perfectly good heads of their own into which similar stuff can pop just as well.
Linguists require specimens of languages to study so that we can understand language. But we have more than enough non-dying languages to keep linguists busy.