One issue with the demo was the fact that it was clearly based on trickery. The person being called did not know they were speaking with a machine. The audience applause was, in part, appreciation of how well the voice bot did its job, how convincingly it portrayed a human.
This is my one and only concern to be honest. I have no issues with the technology existing, I have no issue with it being used - but consent from anyone interacting with it should be gained.
Much as an app asks for your permission to access your data, so too should any software pretending to be a human.