Western culture, for example, has this innate fear of death. This is not a fear that other cultures share.
One could call what these monks were doing mental instability, lack of education or being suicidal. However, from another perspective, one could call what these monks were doing an incredible act of mental strength, self-control and devotion, following their beliefs wherever they lead, for what they perceived to be a selfless act.
I prefer to think that these are people who had a different way of thinking, they lived (and died) ascribing to that, without seeming to cause anyone else harm in their lives. Death was part of a bigger picture for them, not something they feared (or they taught themselves not to fear it).
While I certainly don't ascribe to the belief system these monks shared, there is something that we can learn from this alternative way, and respect in its own way.
Ultimately, I think that's what all compatible belief systems enable... a way of living peacefully and honorably allowing people to explore their own beliefs from life through death, and who knows, potentially beyond.