Because writers are the gods of the little universes they create, eventually they must make hard decisions about their characters. And unless you’re a psychopath or sociopath, the hardest of them all is deciding which characters to kill and when.
Even in genres where it might seem like death isn’t going to or shouldn’t rear its ugly head, like romance, it can be an important background event. But it’s just as important not to overuse it. Violent video games have shown us that too many deaths leave people desensitised. But one perfectly-timed and meaningful fatality might be exactly what your story needs.