Why was PIP killed off?

Could you please elaborate on the reasons behind the decision to kill off the character PIP in the narrative? Was it a narrative choice to create a sense of urgency or tragedy? Or was it due to the actor's unavailability for further filming? Were there any fan reactions that influenced this decision? Additionally, how does this development affect the overall story arc and the character dynamics moving forward? I'm genuinely curious to understand the thought process behind this significant plot twist.