I really wish Microsoft had made UWP cross-platform. Would be pretty amazing if I could use UWP/C# to target Windows, Linux, macOS, iOS and Android properly. With UWP being limited to just Windows I don't see it ever being a success.
https://blog.xamarin.com/preview-bringing-macos-to-xamarin-f...
That's kind of the point. Most apps don't need unfettered system access and many (most?) app authors aren't capable of writing an app that's secure anyway; one of the biggest attack vectors today is through apps.