For the bereaved, it brings comfort and helps the healing process.
If you are making a memory box because you are terminally ill and want to leave a way for your family (especially children) to remember you, it gives closure, and the assurance your family knows they are loved.
A memory box made for Alzheimer's patients will help stimulate their long term memory and allow you to make new and precious memories even in the midst of actively losing their identity because of disease.