I agree that paper ballots are preferable.
But, this is probably not a serious theft of voter data. If Cobb County GA is like the counties in Texas, the equipment used were small laptops with card readers to verify the drivers license is for a resident of the county. In most cases the data is password protected, but probably not encrypted. (it may be that the voter data for the entire state is on the laptop, people do move and fail to change address.)
Most likely, the thief thought he was stealing a laptop. Most thieves won’t have a clue how to start what they have stolen. And if the instructions are with the laptop? They are usually pretty badly written.
Yes, there is some potential for abuse of the data. But I don’t think this is a likely source of identity theft.
Maybe the motive wasn’t identity theft. Who the heck leaves whatever was stolen in a car on a Saturday night?!