Steam Box/Big Picture created because Steam was 'broken'

Valve created the Steam Box & Big Picture mode for their video games service because Steam was "broken" because you can't play in the living room.

In a recent interview with Polygon, Valve product designer Greg Coomer stated that Steam customers have been begging the company to introduce better access to the gaming service at more places. Coomer stated that without the ability to take Steam with you in other places in your house (i.e. the TV) the service was "broken".
“In some ways they were ahead of us in having that expectation,” said Coomer. “They were already clearly playing games in the living room, they had all this stuff that they loved about Steam and it was frustrating for them to not be able to access it in a place that seemed like a natural fit for the kind of content that they were playing.

“Valve was in a position to do something about. We’re uniquely positioned with Steam to have the backend pieces that made sense underneath that interface, so we of course were able to put together an interface. But it’s everything behind that interface that’s the valuable part. There are 50-some million active users of Steam and a huge catalog.

“A lot of people could have built the interface the way we did, but building it on Steam was the fit.”
Valve is looking to compete with next-gen consoles with their own console-type PC.
“We’ve seen a huge movement, just since the announcement and shipping of the Big Picture beta,” said Coomer, “and the momentum and interest from PC manufacturers in building around it.”