Apple pairs Bluetooth with Wi-Fi for a number of features in OS X, so disabling it when not in use with a keyboard or mouse isn't always practical. Putting a computer to sleep or turning off a power switch on a keyboard is less intrusive and similarly effective.
This exploit isn't that large in context of hacks of routers and other gear, and obviously it's not the last of its kind. Billions of IoT devices are coming online in the next few years, and few will be robustly secured or easily upgradable.
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