My thinking is:
1. apps on the Windows Store have some level of sandboxing forced upon them, so I can rest assured that the Windows Store releases of these apps won’t make a mess of their computer, even after major-version updates. (Remember uTorrent?)
2. Windows Store apps get automatically updated in the background without ever running them—like apps installed via the OS package manager on Linux. Give some people any chance to cancel/delay an update, and they’ll do it, indefinitely. Better for most regular users [who aren’t relying on any reflexive professional workflows] to have their apps just “be” the newest version, at all times.
There is also some sort of vaguely-stated plan to allow totally unsandboxed win32 apps in the store at some point in the future but seems to specifically only apply to games.
https://docs.microsoft.com/en-us/windows/msix/desktop/deskto...
The vast majority of the paid software I have consists of games that come from Steam or Gog. Steam really doesn't work well with UWP games, and the Gog stuff I have is mostly nicely packaged DosBox games from an earlier age.