I'm with you. I have no descendants, and even if I did, it only takes 2 generations to forget.
However, the cemetery is an amazing place to also see history (not just genealogy) including art/symbolism and even learning about who the engravers were, to when and why people died. It's really the one place where you can get a snapshot of time of the surrounding community.
I do imagine what it would be like if we didn't have cemeteries... if all of us thought like we did, and I'm glad we have them. We need a lot more people willing to take on the jobs of caretaker, though, to ensure we have these monuments for another generation to enjoy and study. This weekend I had 6 people stop by and chat with me about my work. All were glad I was providing the service and the guy that owned the abutting property even offered to allow me to arrange to get the trees or branches cut down that were overhanging, even though they were on his property, because he could imagine they'd fall and further damage the stones. To get people started thinking about how to preserve these monuments longer make what I do more worthwhile.