Hard Pill to Swallow

What makes people miss a person when they are dead? Will you, I, anyone you know - be missed? Why? What thing or essence or purpose do you now bring to those in your life that will be a noticeable void once you die? Is it feasible or even healthy to live your life hoping or aspiring to people missing you when that day comes? Not "what will people say about you" at some service or gathering. Its expected that those you leave behind will -at the very least- pull some random anecdote or some old feeling up for everyone to share. But when the crowd goes home and goes back to their normal, everyday life - how will their lives be changed on a visceral level? How often will your departure hit them and pause their actions or thoughts? Will those thoughts be positive or negative? Will nostalgia and longing fill their minds, or will it be a guilty sense of relief?