I can see other things being a problem also..
With current linux distributions, you tend to have some rather proprietary installation packages, which result in developers having multiple releases of a piece of software, to suit different distributions; .RPM files for Redhat, Debain used .DEB and so on. I know that more modern distro's dont have so many issues, but still, the vast majority of end users, are not going to want the hassle, or know what is under the hood. They just want something that is going to work.
You may complain about microsoft and bloatware, but you are very much in the minority, this whole forum, is a minority when it comes to the games industry. SteamOS will only succeed if it is released in a highly polished form, which isn't what they will do.
They will release it, and there will be thousands that install it without knowing what they are doing, and they will fall into every trap, every pitfall, and very quickly, they will abandon it, never to look back.
Valve has made their DMC-12, and I for one, wish them luck with it.. they're going to need it.