I am very happy if you can enlighten me. Granted, I do not install Windows very often (otherwise I would bake all these things into an image), and there may be improvements. So feel free to make your point and save me time.

An no, security updates can't run in the background. If I sit a user in front of a PC, the PC has to be secure. Which means that the zero day exploits from a few days ago which are already exploited in the wild have to be fixed. Also yes, software for basic tasks and configuration till usability is reached is part of an operating system install. Otherwise you have to compare the time to install a barebones Linux (1 Minute) with a bare Windows install (still 30 minutes).

I currently use chocolatey for automation of software installs. But Libreoffice alone takes minutes to install on Windows even on fast PCs. If you know a better/faster tool I am happy to listen.