Earlier quoted context omitted.
Decent apps in the actual native store is what the UIKit port is about. It’s not iOS apps on the Mac any more than tvOS apps are iOS apps on the TV. You still need to adapt it to native UI conventions like the menu bar, you just won’t need to rebuild the entire UI from the ground up in AppKit anymore.
Let me put it another way, when was the last time you heard a user ask for an iOS app to be on the Mac? Is this what Mac users want or is it something that Apple wants?
Maybe Facebook will make a Mac client for Messenger (messenger.com works, but some people might prefer a desktop version). Maybe Netflix will have a Mac client (they already have one in the Windows store). We could get Google Maps as an alternative to Apple's native Maps app. Slack could throw away their Electron battery-guzzler and replace the Mac version with one based on the native iOS codebase.
Not every app wants or needs a Mac port, but there are plenty of cases where it could be useful.