I don't think you understood what they're going for. In-Home Streaming is a way to play games in another place in your house, such as the living room. It's pulled off by streaming it to any PC with Windows/OS X/Linux/SteamOS. There's really none of that "social/connected" component to it. It's a convenience feature.
you know what does exactly same thing but much cheaper? frigging cables. It also resutls in better video quality and no extra taxation on your PC.
No one is claiming this is the greatest thing ever invented but, come on, you have to concede that it could be useful, right? Sure, I could run wires all over my house, but why bother when I can now just click a couple of buttons and stream the game. I've read that the input lag isn't bad even in an action game, although that depends on your network. I can't see how it'd be a problem at all for a more turn-based game.
I was wondering if one of the other advantages was that the second PC was also acting as a controller extender. I have a wireless 360 pad, but I don't know how far from the dongle I can get. A lot of people use wired controllers (and keyboard and mice). So, how do you deal with that? I'm sure there's a reasonable way to do so, but that doesn't mean that Steam's home streaming thing isn't an ok solution too.
Not sure why anyone would need two separate devices to do that...?
The point isn't that someone "needs" two devices; it's just that many, many people have multiple TVs/monitors. It's cool if your PC setup is also your main big screen that you use, but a large number of PC gamers have their desktop at a ... umm ... desk. They have a different room in the house with their big TV. That doesn't require a "sprawling mansion". I actually prefer sitting at a desktop for the majority of gaming that I do, but I can definitely see wanting to sit on the couch and play something like The Walking Dead
with my wireless controller. I can do that easily now by hooking up my laptop to my TV and streaming. That's a nice feature, but it's cool that you won't personally be needing it.
This was exactly the type of article I saw and though, "That's a nice, free feature. I wonder how people are going to find a way to dismiss it in the comments". Congrats.