As long as there are no forgotten land mines or other munitions, remnants of war should be a sobering reminder to try to resolve disputes another way.
Every once in a while someone will find some bullets or other artifacts, but nothing truly dangerous. I agree. It's important to not forget these places exist.
To be honest, in my fortunate life, I believe these trenches are the first I've seen that were used in war. Not a recreation or a maintained monument, these were actual fortifications some humans made to protect themselves from other humans trying to kill them.