Why was Spock killed off?

Could you elaborate on the reasoning behind the decision to kill off the character of Spock in the Star Trek franchise? Was it a creative decision to spark a new direction for the series, or was there another factor at play? Fans of the show have expressed a great deal of emotion over this turn of events, so I'm curious to understand the motivations behind the writers' choice. Additionally, how did the cast and crew react to this decision, and what was the impact on the show's overall narrative?