Since so many phones have anti theft feature, it would be useless if phone is shutdown by thief or if internet access is disabled.
The trend of non-removable battery improves security by preventing directly shutting down of phones by removing battery, but the vulnerabilty still lays in lockscreen.
The thief can simply pulldown notification panel and disable internet or just hold the power button and switch off the phone, which completely renders anti-theft mechanism useless.
So it would be beneficial if you add option for preventing notification panel from being pulled down and power button unable to work at lockscreen or
simply block the shutdown feature in power menu and internet access in notification panel when device is still locked.
In this way the thief cannot shutdown the phone nor data connection and hence we can track our device using anti-theft feature making it more usefull.
Battery running low and shutting itself automatically down is another case, but this feature would be more useful rather than having none.