Actually, they're tracking the broadcasting signal to see the location of the devices to see where people are going in the mall, to learn popular spots, etc. It's not pulling your personal information. It's no different than your cell phone broadcasting anywhere else you are at, only difference, they're capturing that signal being broadcasted in the air.
I personally agree with it and see no issue. If I don't want to participate (which I have no reason not to), I can turn my phone off or shop elsewhere.