How is it that death is still a thing in the 24th century?
I don't mean how is it that people get phasered to death, I mean, how is it that any human has to worry about dying of old age? Given the technology on the show, it seems like mortality as a concept should be functionally extinct for most people. Any time they wanted a character to contract a deadly illness, it always had to be some incredibly rare genetic defect or odd space bug. That's because "heart failure" "cancer" ETC no longer seem to be serious medical problems in the world of trek.
If you look at what causes people to die as they get old, the various ways the human body breaks down or becomes susceptible to old age illnesses, none of those health concerns exist in the 24th century. People in Trek should be living hundreds if not thousands of years, and yet no one ever really seems to talk about that. I was watching an episode of TNG last night where a female admiral was talking about how she had no time to waste since she was now 100 years old. This part was played by a woman in her 60s. Let's assume then that most people in Trek live to be 150 or so, based on that actress' real age and the age of her character.
How come people can't live for millenia on end in Trek? Can someone with some tech knowledge of the show explain it?