The thing is, SteamOS is not Windows, so the developers will have to recode and optimize for it. Why doing it if you only have a few steam machines on the market, and why doing it if some steam machines will run games an others dont. I only see them as a living room expanded thing that receives stream from a big PC and that only some pc gamers will buy. As how it is, they will start slow and continue slow. Anyway, we can talk about it in two years to see who was right.
SteamOS is not Windows, yes, but it's Linux and on Steam there are already 2395 Linux games and rising
And more and more games get Linux and MacOS releases.
Please excuse my bad English.
Currently gaming on a PC with an i5-4670k@stock (for now), 16Gb RAM 1600 MHz and a GTX 1070
Steam / Live / NNID : jonxiquet Add me if you want, but I'm a single player gamer.