I personally would want people who I know and love while I am alive to forget me and move on with their lives after my death.
It’s like I would be happier in whatever is in the after life to see the people who I cared about happy with their lives, instead of getting sad whenever they remember me or worse yet, remembering me on yearly basis after I am gone.
I genuinely find it very illogical and selfish for people to want everyone to never forget them long after they are gone, especially due to the pain that come with memories.
That is why I am curious about the reason.
I think there are two different things at play there, and both have been mentioned, so all I can add is that it’s not one or the other but both. (Well - that and a song)
Partly it’s the common human need to feel that we matter - that our lives are in some way significant.
And partly it’s the fear of death and the resulting desire to believe that we’ll “live on” at least figuratively.
And the song is from Shriekback and is directly on topic - Dust and a Shadow