Linux needs more apps that GUI friendly and easy to use, better support for hardware and upgrades that doesn't break easily. Should come pre-installed with PC. Most people don't bother or know how to change OS.
The odd thing about this is that because Linux generally doesn't come preinstalled (though some sellers do have it), I've found the Linux installation process is usually smoother and easier than installing Windows.
I realize it's extra work, though, which is a barrier for some. Worrying about screwing up their new computer and voiding the warranty is certainly a deterrent.
Having worked with preinstalling Windows with a major pc manufacturer, I will say that it is already such a freaking effort that nobody would want to do even more effort to install malware on top.
Notwithstanding so called partner apps... If there's anything in those, I can't say.