It's not a problem of design, appearance and what not, but function. Nobody wants a desktop anymore, even a sexy open-platform desktop, except for gaming, because frankly, there is no need for one. If you want power for gaming and work, you get a desktop. If you want good looking power, build an m-itx / m-atx beast that take 1/4 the size of a regular tower, and will look good next to the hi-fi. People have been trying to sell custom desktops forever (Alienware, Dell, HP...), and nobody bites. Enthusiasts would rather build and upgrade them themselves, and casuals just don't need them and would rather have a tablet, console or notebook.
The home management PC has been done before. Often too expensive, too complicated and largely superfluous (why get a robot to turn on the lights when you can do it yourself). Sure, you can build your place around a centralised computer system (alarms, AC, voice commands, robo-butlers), it's usually the domain of the enthusiast or the rich geek, we aren't quite there yet for mass appeal.
And BTW, I wouldn't want my gaming PC doing all that stuff in the first place. Hell, I'd want to isolate that sucker waaaay away from the internet, and not have someone mess around with my household appliances.