My mistake, I thought you could specify any hour (even peak hours) as your hour of power. I agree with you, but that's only if people shift their normal usage to the hour of power. As we've already seen, people see it as a challenge to use as much power as possible. For example, you may normally run one heater, but with the hour of power you decide to run one in every room of the house.
Yes you can do that cos you can. But if the desire is reduce the bill, we would want to shift what we will use anyway, to the free hour. I can see some tiring of that, and others making it the norm to run the washing machine and dishwasher same time every night, give the rooms a free boost of heat. Its not a magic bullet, but its something very worthwhile