In non-Pro/Enterprise editions of Windows the software still generally (though not always) respects the registry keys in HKLM\Policies, they just remove the tools to configure local group policy and (obviously) you cannot join a domain to set them through AD. You can still use third-party tools like PolicyPlus combined with the freely available ADMX packs that Microsoft ships for installation into AD forests to set whatever the hell you want.
Microsoft will update settings in an update at a PM's whim.
They may break registry key bindings due to code changes.
But they generally don't break gpo functionality, because this causes issues for $$$ enterprise customers.
Downside: Believe they cut group policy functionality in <Pro OS versions.