Not much point to a dedicated Steam OS machine if there's no compelling software being made for it. Not even exclusive titles, but new titles that will release alongside the other consoles/Windows PC versions and not months after when they're finally ported to Linux/Steam OS.
I think if Valve can even get one big name publisher (Bethesda, Activision, etc) to support their platform with new releases, the others will follow suit once the sales are proven to be solid.
The OS has only been out for barely over a month now and Steam machines arent planned to release until the later part of 2014. Why are you expecting so much so soon??