Back when wireless home networks were becoming popular, I used to warn my friends about making very sure they were extremely secure.
What I told them was having an unsecured wireless network was like running a network cable from your router out to your curb and letting anyone passing by plug it in.
Looks like any WiFi capability might be turned into a similar hazard.
I remember the upset about wireless Nanny Cams. They would broadcast a view of your child's room that could be received by anyone in the area monitoring that frequency.
By watching for a bit, they would learn exactly what room it was by the light being turned off and on and the layout of the room so entry through a window and a snatch would be quick. They would also know when you had left the room and the kid unattended. Not quite as bad as putting your kid's bed out at the curb, but damn close.