Today I'm shallow, I found the accompanying story of Wayne Gretsky's daughter more interesting. I'm also considered cruel and uncaring by some people.
I admit I did not read the whole story on the suicide forest. I've learned if someone wants to commit suicide you can not stop them. Just don't work, if they really want to do that they will find a way somehow. Go play with a Grizzly, worked for Treadwell. Go camping during an Alaska Winter, and don't take any food. Not only will you perish, but you will become famous. people will trudge to your death site and pay you homage.
As others have said before me, it helps clean the gene pool.
Some societies look at self inflicted death different than we do. A long time ago in the society of Native Alaskans living along the coast of Northern Alaska they looked at things different. When the Elders became too old or too feeble to be a productive member of the group, they took a long one way hike out onto the ice. They went out to meet Nanook. They faced Nanook with courage, they had lived a productive life, and it was now time to move on.
Yet I somehow doubt that these people in Japan are looking at it from that standpoint. They have other issues that are driving them that way. A phycologist friend once said they are just unable to deal with life.