As you said in your list, it's used by many a company that obviously see the benefits.
Where it is not used however is in the masses. Between my current highschool and the tech school I went to before that, I have only met one other person running a Linux system. Out of thousands.

Android might run phones and UNIX may run servers and Linux may be on all of Pixar's workstations but for your everyday consumer, windows is king.
Most of the laptops that come bundled with Linux are either some hobbyist company like thinkpenguin or dell,slapping Ubuntu on cheap hardware.
I don't think people are ready for a change, just see this:
Ubuntu causes girl to drop out of college -
https://youtu.be/5Qj8p-PEwbI

There is also the fact that some people don't care. for them the computer is a needed evil that types word docs and sends emails. They don't want security, don't want power, flexibility, or privacy. They just want to turn it on, type a little and get off.
Linux would never appeal to someone like that, at least not yet. There is a part of me that doesn't want it to.
I feel as though if Linux tries to beat windows, by becoming windows, no one benefits at all.
Or just that when you try and make it easy enough for everyone and their grandmother to run that you lose something.