Perhaps the essence here is precisely that many feel this nostalgic loss of something that never existed. Seems to be part of the human psyche... just like the passing of time often leads people to a place where someone who betrayed them "actually wasn't that bad."

Staying objective about the past isn't easy, mind you... the older we get, the more cynical we become, so often what we miss isn't the actual times of the past, but a version of ourselves that viewed the world through more rose tinted lenses...