This is pure speculation and I'm nowhere near qualified to speak with any accuracy, but perhaps it's the case that the processing requirements would reduce batt

This is pure speculation and I'm nowhere near qualified to speak with any accuracy, but perhaps it's the case that the processing requirements would reduce battery life too quickly. Although, having said that, "Hey Siri" only works when the phone is plugged into a power source, unless you use a jailbreak tweak to turn it on all the time.