Hi @leptiotgerard,
If you have an antivirus active, try disabling it for the install of MSFS.
I’ve only had this decompressing issue once - when MSFS first came out. I did what you did by ending task, delete the file, relaunch and it picked back up.
Also, I’ve done this as well… the file that is decompressing can actually be opened in 7zip or WinRar and you can manually extract it.
And I do agree that more design should go into how MSFS downloads / extracts. There are several wishlist topics on this:
Decompressing Wishes:
Search results for ‘decompressing category:163’ - Microsoft Flight Simulator Forums
Installer Wishes:
Search results for ‘installer category:163’ - Microsoft Flight Simulator Forums
Reinstalling from DVD: You shouldn’t have to use the DVD’s for reinstalling (someone can correct me here! @Neo4316 
). If you are logged into the MS Store with the same account as MSFS/Xbox, it should show up in the MS Store for download. https://forums.flightsimulator.com/t/re-installing-dvd-version-on-new-windows-install/399596/10 and https://forums.flightsimulator.com/t/re-installing-dvd-version-on-new-windows-install/399596/25