It comes without an operating system, any storage, a case, or even a power supply. This is a huge, if not insurmountable, barrier to entry for a large portion of the population.
The Chromebox is a turnkey, plug in power, plug in TV, surf the web product. They couldn't be more dissimilar.
Just a quick note: The biggest piece of feedback I got from a journo friend of mine who just reviewed this chromebox is actually that out of the box it won't do HDMI or VGA (without buying an adapter separately that is), which seemed odd to me (and to him) given being easy to connect to a TV seems like a big use case for the chromebox.
edit: In case anyone wants to see his hands-on piece, it's at http://www.techradar.com/reviews/pc-mac/pc-mac-desktops/sams...
Some DVI ports can send VGA signals, in which case it would just be a matter of getting a cable with DVI pins on one end and VGA pins on the other.
In other words, the DVI spec contains a VGA-compatible part and an HDMI-like part so that a single DVI port can send VGA signals or HDMI-like "DVI-D" (DVI digital) signals.
Moreover, DVI-HDMI cables are common although some DVI ports cannot provide audio to go along with the video and others cannot speak the High-bandwidth Digital Content Protection protocol.