They need to do a basic rethinking of their OS, which should really move to a “tailored fit”, with ala carte add ons.
To start with, MS would make “ideal” basic platforms for major end uses, stripped of everything not essential to those particular uses.
But users could also design their own out of major compatible pieces, like assembling a jigsaw puzzle, leaving it up to MS to troubleshoot their basic designs to show them any problems or gaps in their design. Users would tell MS all about their current hardware and software.
Then in either case, users would be able to add functionality on a sliding scale from free to large packages. There would be a running tally so they could add up to their budget limit.
Then finally, once a functional design was reached and troubleshot, MS would download it to them as well as send them reinstall disks in the mail.
It is also the gift that keeps on giving, as MS would sell a maintenance package that would not only optimize and protect their install, but upgrade it as needed, especially when new hardware or software was added.
I know how they could do that - people could put the programs they use in a system variable called PATH, then put that in a file called AUTOEXEC.BAT, then put all the drivers they use in a file called CONFIG.SYS.
I’m convinced there’s a boatload of stuff in your basic MS operating system that both MS and the USG would rather not know was in there.
Strip it all you want and it will still be massive.