While I think something like this makes sense, the pricing seems off. For $600 you can build a PC with a desktop GPU. If you want to make it easy to set up, you could just use an off the shelf mini-PC and preinstall everything so a non-technical user can get started without any hassle. I really hope we’ll see more Steam machine like devices in the future.
Based on their web page, I think what you’re paying for is not having to learn how to configure this stuff.