Turning Airplane Mode on and then tapping the Bluetooth icon will fully disable Bluetooth (gray background, not white). You can also just disable it in Settings. Apple’s argument, as I understand it, is that Bluetooth and WiFi don’t actually consume much battery, but non-technical users would habitually disable them to save battery and then complain that Location Services didn’t work well. Hiding the setting but keeping an essentially useless toggle prevented those non-technical users from making their device function worse while still letting them feel like they were saving battery life.