Valve wouldn't exist if it weren't for the PC. Id Software, Epic, Zynga, Facebook and Google wouldn't have existed without the openness of the platform. I think there's a strong temptation to close the platform. If people look at what they can accomplish when they can limit competitors' access to their platform, they say, "Wow, that's really exciting". Even some of the people who have open platforms, like Microsoft, get really excited ... That's not how we got here, and I don't think that's a very attractive future.
For Newell, one thing holding Linux back is the absence of games. Valve's efforts with Steam and supporting Linux are, in part, a "hedging strategy" against things going bad with Windows. Valve recently launched a Linux-specific blog to add more insight into their work on the platform.
I think that Windows 8 is kind of a catastrophe for everybody in the PC space. I think that we're going to lose some of the top-tier PC OEMs. They'll exit the market. I think margins are going to be destroyed for a bunch of people. If that's true, it's going to be a good idea to have alternatives to hedge against that eventuality.
The rest of the wide ranging interview is a fascinating insight into Newell's thoughts on 'touch' as a shorter term transition interface toward future 'post-touch' concepts, as well as the corporate culture behind Valve's success. The interview in full is available at VentureBeat.