To bad Linux operating systems are NEVER completed and the choices of software for any Linux OS is scant... Gaming on Linus OS's will never fly.. Most Linux operators are to poor and use all free software
Ok so lets see If I can help shed some light on this. As a long time linux user (ever since 1997, thats before some of you had been born, keep in mind) Linux has PLENTY of apps to choose from, just not in the normally traditional "download installer .exe/.msi, install, never get real updates again.
I am going to assume that @maxxxem1 has NEVER used a linux distro the first day of his life, as how he seems to be spouting traditional MS fud.
Anyway, the whole thing of it is this, with Windows 8 having The Windows Store, it becomes a mostly closed off ecosystem. You see, back in the Windows 98/2000/XP days Steam stared up selling apps, and MS did not care. But now that 8 has TWS, Valve thinks that Steam will lose sales. Mostly because that TWS is where people will go to buy games, not to Steam. And they are right, the average, non-hardcore game WILL go to TWS first. Infact, to be honest, if you are NOT a Steam customer/games, then you have no idea that Steam even exists, and as such, Valve loses money.
Now Linux, who has SHIT TONS OF APPS, just needs more games. Not that Linux does not have games in general (I just opened up Ubuntu Software center, and went to "Games" and it says 698 games available.. ) It is that most linux peoples would like commercially available games. The Humble Indie Bundle's have done excellent in showing that Linux gamers will pay on average about twice as much for a game (keep in mind, "twice as much for a HIB" = like $8 USD for 6 games.
So yes, by Steam moving to Linux, the theory is that the truly hard-core, serious PC games will go to Linux also (and some will) and that Valve will inherit the Linux user base as Potential Clients. TWS is going to make the app store a closed ecosystem to everyone one but Microsoft, like how Apple has done for the Mac.
And one last note to @maxxxem1. Any, and every single time MS releases a fix of a patch for Windows just goes to show that the Windows OS was never "completed" as how you said. No OS IS ever "completed", ALL OS are just "Stable Enough for Current Use on a Day to Day scale". So learn something before you open your mouth again.
Also, a current rumor is "The Steam Box" a Specialty Linux Distro made all around Steam for Linux, with it's own customized Ubuntu, eventually made in to a PC/Console hybrid Gaming system. Thats the rumor... May take a few (5-10) years though)