Most people miss and grieve for loved ones when they die. I think it simply comes down to that- they don't want to go through that pain until they have to. Parents likely hope they'll never have to go through it over their children. They likely assume that they will die first. But, a death in the family is huge to a lot of people.
I suppose I find it kind of odd when people talk about death so flippantly. I always kind of wonder- is it because they haven't lost anyone that close to them? Or, did it just really not affect them?
Mostly why I get so unhappy is because I am still grieving for my family members that have died (none of suicide.) Losing someone close to you can potentially tear your life apart. I imagine it can be so bad that it leads to more suicides in fact.
But basically- rather than maybe a few years of mourning someone, they could be facing a few decades. And, I think the pain a suicide causes is different to natural death. In fact, I suspect all types of deaths create slightly different feelings in the mourning process. A death that is expected due to old age and illness will likely still be upsetting but, perhaps the person will have been preparing themselves mentally. Someone who dies suddenly, in an accident, is murdered or, commits suicide is going to add shock and even guilt into the mix. Could they have been saved?
I think you quite often see anger after a suicide. As in- how could you have put me through this? It's got to be upsetting really that we do it deliberately, despite knowing how much it will hurt loved ones. Still, I think that's more societies fault at large. If we were more able to talk about suicide openly, people would have more of a chance to prepare themselves for it before it happens. Plus, they'd have a better grasp on why it happens. Some people may even be able to be helped in time. I think the way suicide is treated in our societies- as in absolutely forbidden to be discussed, is so counter productive.