Consoles aren't for geeks. They're for average folks. Folks who don't want to have to upgrade stuff. This Steam box is basically a PC that runs an embedded (Linux) OS. It'll still require upgrades, compatibility issues, inconsistent performance, etc.
And Sony never has to upgrade the console. Like when they did it and took away the ability to dual boot Linux. The PS3 is basically a purpose built PC that runs a locked down Linux, and still requires upgrades, and has compatability issues with early titles. (PS2) The Xbox is basically a purpose built PC that runs a locked down Windows, and still requires upgrades, and has compatability issues with early titles. Your phone is basically a purpose built PC that runs a locked down Linux, and still requires upgrades, and has compatability issues with early apps.
Are you seeing a theme here?