Personally I don't think SteamOS is suited for much else than running Steam. Now I have not tried it so I can't say for sure, but I have a feeling they made this distro for that purpose alone. And since we already have Linux Steam, I don't see the need to switch so SteamOS. The way I understand it, is they wanted to make a distro specifically suited for a gaming console to run Steam.
Personally I am quite happy that they chose to base it on Debian. Now my opinion here is very biased, but I think Ubuntu is doing the wrong thing to develop their own window server, mir instead of going along with wayland. I have read many that regard certain decisions made by Canonical to stray too far from the rest of the Linux ecosystem. I am happy that Valve decided to not tag along with that.