Yeah, I already use update-notifier and mostly it works really well, but for anything which requires user intervention (like changes to repo locations or installing aptupgrade) it doesn't really help because it doesn't tell the user that they need to do something. It just stops updating.

Of course not! That is not and never was what it is intended for.
I'm not suggesting a new notifications app, just a Synaptic or update-notifier message that just said e.g. "please go and download aptupgrade now" when something like that was required. It would only be used for crucial stuff where otherwise the system would stop updating, so wouldn't be invasive.
So you want someone to recode an existing app for you?

That would be as much work as coding a new app and as invasive. I think you do not understand what you are asking for. Pop-up messages are invasive. Did you never use a pop-up blocker on your windows?
It's just a suggestion to make PCLOS more intuitive and friendly, especially to newbies and/or people who actually use it on work machines rather than for developers.
PCLinuxOS is not and never has been a developer's distro. It was created and is maintained for
home users.
IMHO it's already the best distro for this type of user anyway, but over the last couple of years I've seen so many posts on here from people saying "I didn't know I had to update it regularly" or "it didn't tell me that it had stopped updating itself" or similar. Seems like this is one area where users find it less than intuitive, and I can see why. Phones update themselves without needing user intervention. Users who are moving over from Mac and Windows will expect auto updates without having to manually change something every now and then. Even TV set-top-boxes and stuff like that download firmware and update automatically, or warn the user if any action is required.
Menu > More Applications > Configuration > Configure Your Computer >>> give root password when asked >>> System > Manage system services by enabling or disabling them >>> put a tick mark beside APT (about the fourth entry down). Your system will update each time you boot up. This was posted about previously by Texstar.
Linux is not windows. It never has been. If you expect us to rewrite all the code to make it 'just like windows,' prepare to be disappointed.
It is quite easy to get the news from PCLinuxOS -> the home page - Software Announcements - twitter -< all are easily accessed. We provide the news and announcements. It is up to you to read them. In other words, it is your responsibility to take care of your system. We do our part by providing the system, updates to the system and news.