For
It saves money and simplifies communication.
Against
It excludes speakers of other languages and reduces fairness.
Anonymous excerpts, translated where noted.
“By that logic then English should be the only official language as it is the lingua franca all the world follows.”
“No need for a variety of languages.”
“Portuguese should undoubtedly be one official language of the UN.”
“Personally I’m for adding some other languages to the official language list.”