Elder Dallin H. Oaks: National Guard
When I was seventeen, I joined the Utah National Guard. There I learned that a soldier must use certain words in speaking to an officer. I saw this as another mark of respect for authority. I also observed that this special language served as a way of reminding both the soldier and the officer of the responsibilities of their positions. I later understood that same reasoning as explaining why full-time missionaries should always be called by the dignified titles of elder or sister, or the equivalent in other languages.
The words we use in speaking to someone can identify the nature of our relationship to that person. They can also remind speaker and listener of the responsibilities they owe one another in that relationship. The form of address can also serve as a mark of respect or affection.
So it is with the language of prayer. The Church of Jesus Christ of Latter-day Saints teaches its members to use special language in addressing prayers to our Father in Heaven.