After people spend a few decades on this sphere called Earth, they're really just going through the life labeling everything they already came across, and having really iconic representation of things, without really paying enough attention to the details. That's why it's a bloody hell to be at the age you were supposed to have a grandchildren but having noone.
It's not just tough because of the loneliness you might experience, and the sense that you haven't left much behind, but grandkids are especially important because they look at everything in awe, with eyes fully open and surrendering to every experience. This makes them feel alive again, and show's them the freshness of things which they haven't seen for a long time just by themselves. :)