I think Ron hit it on the head. The motivation letter brings a human quality to a financial transaction.
One of my buyer's was asked why she was buying another property when she owned and occupied another residence a few cities away. She started talking about how she grew up in the community as a child and always loved that home. The family that lived there were kind to her as a child and their daughter was her best friend. More than 15 years ago the family lost the home to probate when her best friend from childhood died from cancer. She described how much she always loved the backyard and the large tree with the swing, that remains to this day. She wants her grandchildren to know the feeling she had at her best friend's home as a child. Then she spoke of how in a few years she will retire and wanted to live there for the next 30 years and pass it onto her daughter, etc.