There is indeed an approach to locate phones based on the signales from Wi-Fi routers. The challenge is its accuracy which is not better than 6-10 metres - so it's you are in this room or in the other room.

With cheap and tiny Bluetooth Low Energy beacons the accuracy could be down to inches. So it's about you being at the front-door, at the check-out, in front of the mirror, next to sofa bed in the furniture store, etc.

It's much more precise, thus the context for the app on the phone could be better and the experience almost magical.

And also Bluetooth Low Energy is fully supported by major phone companies (http://blog.bluetooth.com/os-season-what-it-means-to-you/) so BLE beacons like our motes could trigger different actions based on your location even if your phone is in the pocket.

You can't do it with Wi-Fi and AP infrastructure and since the beacons are wireless, cheap and easy to install there will be eventually new infrastructure build.