Statistics are in favor of young people not thinking about death a lot. If one grows up in a healthy working class/middle class community, death will occur primarily among the elderly. Some will die of accident or disease (at any age) but most young people will not be close to that person. For those young people who are close, it will be to varying degrees traumatic.
The rate of death in some communities is much higher than others. A young black person living in a high crime neighborhood is more likely to know someone who died by gunfire than a young white person living in a calm low-crime neighborhood.
Another factor in how often one will be confronted by death is how much community life one participates in. Many families have fairly limited community involvement. They don't belong to churches, social organizations, don't participate in scouting, extra-curricular activities at school, and so on. They are fairly isolated. That decreases the likelihood of knowing people who die.
So... they haven't encountered people dying; they are young; why would they talk a lot about death?
All that aside, I think it is good for people to think about the future deaths of themselves and people they know and love (or like a lot). Sooner or later, it's guaranteed to happen. Becoming familiar with the "idea" of death makes it less scary. Thinking about what people go through on their way to the grave should help clarify their thinking about what they themselves are willing--or not willing--to put up with.
For instance, if one is diagnosed with a fatal disease, it isn't necessary to "wage a war against one's cancer". When people are diagnosed with cancer at a probable terminal stage, radical treatment (surgery, radiation, chemotherapy, etc.) may not be worth it in terms of added suffering. If one hasn't thought about death and dying until that moment in the doctor's office where you hear "the prognosis is not good", it will be very difficult to make congruent personal decisions in the days and weeks ahead.
I'm not saying that one should be ready to throw in the sponge at the first mention of cancer, heart disease, COPD, or various other pieces of bad news. But thinking about death and dying ahead of time will enable one to make a more measured response.
A friend of mine who had become immobile because of obesity, circulatory problems, and injured joints, was not enthusiastic about life. When she was diagnosed with uterine cancer (usually a fairly slow, curable cancer) she decided to not get treatment. She felt she had nothing to live for. She had, in fact, passed the circumstance where she said she would commit suicide (if she couldn't get around and take care of herself). Unfortunately, she found that once one is in that situation, suicide is much more difficult to arrange. Even if she had been willing, she would never have been able to get to a bridge, crawl over the railing, and drown herself. Her collection of drugs had been confiscated by a nurse (suicide risk), so just letting the cancer go was her "best option". She died in her mid 60s.
She had been a nurse, knew what she was in for, and pursued it anyway. I had known her for 40 some years, and her actions were entirely consistent with what she had always expressed.
Her choice was suitable for her. Other people have to face their own circumstances and decide what to do.