I'm sure all of us would agree that one would prefer to keep our mental health perfectly intact. However, with mental illnesses often comes the presence of a rare gift. For example though autistic people can often not perform simple tasks such as daily functioning or social comprehension, many have extraordinary talents such as the ability to memorize a dictionary, play a classical piece on the piano after hearing it once, or solve nearly impossible math problems. Manic depressive people sometimes have great talents for comedy. Mental illness can inspire musical, visual, or theatrical creativity. Van Gogh suffered from epilepsy and hallucinations, but he is one of the most renowned painters in history. Antonin Artaud was a schizophrenic, but he is one of the greatest theatre masterminds of history. Of course, mental health is always preferred, but if that's not a option, it's nice to know there are still some "perks," so to say.
Unfortunately this is not the case for those who suffer from severe amnesia. Those who cannot remember much of their past and have difficulty encoding new memories suffer in more areas that simply forgetfulness; due to the fact that so much of their memory has been erased, those with amnesia tend to have far lower imaginative and creative skills. Think about it. If someone told you to paint a sunset over mountains with trees and flowers but you had very limited memory of these things, you would not be able to complete the task well. You would certainly not be able to come up with imaginative ideas easily on your own.