Earlier quoted context omitted.
Replace "language" with "race" in that sentiment and you'll understand how dangerous your sentiment is. Languages are not mere vessels for communication. They also hold within them cultural histories and ways of thinking. To want all of them eradicated but one is to proclaim one language "superior" to all.
"race" is just how humanity likes to self-segregate. "language" is a tool used to communicate, and it would be wonderful if any two arbitrary people could successfully communicate.
Luckily, we have technology that helps us translate between languages almost instantly. This allows people to communicate without completely eradicating an aspect of their cultural identity.