Is the renaming of past events important?

The US congressional has voted on a non-binding resolution recognizing the massacre and deportation of Armenians living in the Ottoman Empire as Genocide. 

Turkey which rejects calling the event a genocide has warned that it will harm relations. 

It refers to an event which happened nearly a century ago under a government that no longer exists. But the response on blogs shows that what the U.S government calls it is important.