The same goes for Wi-Fi in the case of the recent Broadpwn set of bugs, which affected the iPhone and most Android devices and made it unsafe to leave the Wi-Fi auto-connect feature enabled.
In Apple's detailed documentation, it is clearly stated that iOS 11's Control Center doesn't let you turn off Wi-Fi or Bluetooth completely so that users can take advantage of iOS 11's other important functions. The new LTE Apple Watch is supposed to be more of a standalone device than the previous models, able to use cellular data rather than relying exclusively on Wi-Fi, but the reviewer found that two separate Apple Watches both experienced the same problem of trying to connect to unknown (and potentially dangerous) Wi-Fi connections rather than switching to cellular. According to them, not everyone is aware of this and will use Control Center to disconnect from Wi-Fi and Bluetooth, not realizing they left them on.
When tapping on the two icons, it shows that it becomes disabled, however, this does not actually turn off the radio for both these features.
Turning off Bluetooth and Wi-Fi reduces your exposure to potential attacks to hardware, firmware and software, so "it's good practice", Barisani told Motherboard. Apple, however, confirmed that this is not a bug or an issue with the operating system.
But what if you actually want to save battery juice by turning off Bluetooth and Wifi? Those are already good reasons to turn them off, if not used. One aspect of it that may have, at least at first, appeared like a big plus is now proving to be a bit of a security and usability problem: the Bluetooth and Wi-Fi controls. Fortunately, there is still a way to turn off Wi-Fi and Bluetooth altogether. You can go to Settings and hit the toggles for those features there.