"Absence makes the heart grow fonder"

I am not quite sure whether it is absence or distance but then both have the same effect. Why is it that we tend to value people more once they are gone? Why do we reminisce the good times we shared when they are not near but bicker about anything and everything when they are? It's a common known fact that works of art fetch greater value (running into lakhs and crores) when the artist is dead, whereas he would have have died of poverty coz he couldn't manage to sell even one of his works.

Why can't we cherish our loved ones when they are right here with us? Why can't we leave all our bindings and just live the moment? Why is it that we realize true love only when we bid farewell? I know these a lot of unanswered questions and frankly speaking I have no clue. But then if I had all the answers what would be the point of living? Life is a journey, we learn along the way right till the very end.