Beacons are much more precise than GPS. You can setup more than 1.5m accuracy and they can have built-in sensors (e.g. motion sensor). So the signal is broadcasted (URL opened) when you touch something for example.

As you know beacons use Bluetooth Low Energy - it is different Bluetooth and really low-powered. Beacon can last many years on a single coin battery. It's also way more power efficient for the phone to scan for beacons that GPS regions. Beacons have almost no impact on phone's battery.

In addition it is important to remember that 80% of time people spend indoor when GPS doesn't work, so that technology might be useful for indoor applications (e.g. museums, airports, retail, etc).