Why would someone want to write a poem or song in more than one language?

When someone writes a poem or a song in more than one language,this person have an international objective.It helps the person to understand very well the languages and it gives chance to this person to make understand his write by many people because poems and songs are not just words,they reflects our sentiments and our desire. If this person writes in French only, someone who speaks English or other languages will not be able to understand it, but if he writes it in many languages, many people could understand it. Also,if someone writes in just one language, it will seems like this person doesn't want to share his ideas and sentiments with others cultures and languages.
By writting a poem or a song with more than one language, it includes more than one audience because people from every where,could be able to understand the song or poem, to sing it or recite it, and to compare it with themselves.