When was the last time you received a handwritten letter? For most people it has been a long time, maybe years. There is something really special about finding a handwritten letter from a friend or loved one in the mailbox. A part of the person is there on the paper for you to see. The handwritten letter is personal.
Would you rather receive a handwritten thank you note or an email or text thank you? Most everyone places a high value on their time so a handwritten note indicates the writer feels your generosity is worth the extra time it takes to hand write their appreciation.