They have signal where other devices don't, and, most importantly, Bluetooth does not interfere with 2.4GHz WiFi in a crowded apartment building in a crowded street.
This makes a world of a difference. With my previous laptop, I simply couldn't use wireless internet simultaneously with Bluetooth unlesss being in the same room next to my router.
With apple client hardware and the same router (it also supports 5GHz, but I'm not sure if that's the underlying cause as it still works great on 2.4GHz with the MacBook), WiFi and BT work flawlessly across my whole apartment.