"Criminals no longer need to stake out a home or a business... because energy usage often drops to near zero when a house is empty, the readings could be used to identify which owners are at work or on holiday."
Or they could just ring the doorbell.
Yet another "security" thing that has absolutely no concept of how a malicious agent would actually act. Hell, it'd be easier to just wait outside the house in the morning in that case.
I'll let you into a little secret. Most people work 9-5, plus travelling. Chances are that most houses in your street are empty at those times except for those with stay-at-home parents (who are likely to be out of the house when school is starting / finishing on a school day, if you'd like to try that too).
Sure, maybe you could tell REMOTELY (i.e. from working at the energy provider) who is in and who is not. But the accuracy of someone who uses gas (without a smart meter) instead of electric (with a smart meter) for heating in the same house, or someone who has their own solar panels but doesn't feed back to the grid, or someone who actually prefers a colder house, has energy saving bulbs, etc. is no better than those who will / will not answer the door when they are in.
Hell, even the "burglar's broadcaster" of a light that comes on or goes off at the same time every night is useless and NOT used as a signal to a burglar (my front porch does it, whether I'm in or not) even though if you monitored the property enough it would be quite a good indicator.
If you wanted to burgle houses en masse, you wouldn't mess around with meters. What you'd do would be to phone the property, ring the doorbell and/or collect lists from things like airport car parks (who often require your home address and where that could be accessible to someone willing to sell that list for some quick, untraceable money).