The moddability is a deliberate strategy by Valve, and I don’t see it as an inevitable move for every PC-centered company, Microsoft being the prime counterexample.
Lots of good stuff there, too. XBMC for life!
And I still use 2 original Xboxs at LAN parties here and there. Even with a softmod and Linux, it's still possible to system link Halo, Halo 2, Battlefront (2004), Battlefront 2 (2005), Crimson Skies, Metal Arms, and other games across at least three generations of console (Xbox, Xbox 360, Xbox One) with 16-to-32 people. Microsoft does backward compatibility like almost no one else, even on console.
It's getting harder to find replacement controllers, but I've found a local hardware guy in my city who can help find the right replacement parts as little pieces on the board start to fail. I plan on keeping both of mine running as long as possible!
But yes, Valve does seem to get what gamers want (other than games made by them)