I feel it could be useful in some cases, though for their examples, it will fail for most devices. For example, many TVs do not respond to a TV remote for a few seconds when plugged in. For example, on my TV, it takes about 4 seconds before it will even listen for the remote, thus the case will be how long can that device keep the current flowing after it receives the initial trigger.
It will only really be useful for sensor type devices that can be woken up almost instantly so no special initialization process.