In response to newsonline- I can attest to the build quality of the device... it features a steel and aluminum construction and is quite solid. We can debate the looks of it, because that's subjective (I found it sleek and elegant, some prefer edgy and flashy). MXM cards are indeed expensive, but the interface in the Deskmini is quite accessible and not all that hard to replace (say, if/when MXM 1180s arrive).
The size of the Deskmini wouldn't permit for a short-board (mini-ITX) graphics card as you suggested... I suppose you really have to see it next to something to get the scale of how small it really is, but it's only slightly larger than one of those types of GPUs. Thunderbolt... yes. The lack of it is somewhat disappointing, but the next-gen interface only has so many applications, many of which don't apply to mainstream users. However, I understand your disappointment with the MXM GPU form factor and interface... the Deskmini may not tick all the boxes for users looking for those things in one small package. But I believe it ticks a lot of the boxes for someone considering a product of this kind, especially if you look at other devices in this category and enjoy the DIY approach but still want to go the barebones mini PC route.