For a tech-savvy user, there probably won't be much of a point to switch to steamOS, especially if you already have a decent PC with steam (either windows or linux). It's a different situation for those steam machines, though. Since the hardware producers obviously have to ship it with an operating system, the question is which one. Sure, valve could cook up a debian fork with some extra driver tweaks and a different default interface...but from there, why not go a tiny bit further and call it your own OS?