Of course, someone could watch my house now and see when I turn on my lights. Better yet, they could see me stumble in when the bars close at 2 am. The issue isn't that private information is being made public, it's that the cost of gathering and aggregating public information is being drastically reduced.

Without smart meters, it might cost someone hundreds or thousands of dollars to hire a private detective to discover my drinking habits. My estranged spouse might be willing to spend that money in a custody case, but my life insurer wouldn't find it to be cost-effective. With new sources of low-cost data like that from smart meters, the calculation might be different.

(edit: corrected a couple of typos)