I personally always enjoy Meta update posts on other instances to see what they're up to, how they handled a particular problem, or offer help if they need it, and welcome the same on the meta posts on my own community from non-members.
Same. As an instance admin, I like to read other admins' experiences with new version updates and being aware of possible attacks/issues in the fediverse.
because it affects the communities too, lots of outside accounts use the communities here
if there's downtime for the instance or database issues or something, then subscribers to c/programmer_humor or c/programming might want to know because it affects them too