"Glass" as a material could be a fine choice for a desktop. We aren't talking window glass here, but rather any number of high-performance materials in the glass-ceramic family. The current iPhones structures are essentially 95% "glass" these days and see a much more demanding usage application than does a device that spends its life sitting on a desk inside a building.
Rather than the material used, I see the main concern with this design to be user access for repair or upgrades.
I strongly doubt Apple will share your concern about user access for repair or upgrades. Of course we should able to at least swap out SSDs and (laptop) batteries in a simple manner but that's just not the Cupertino way.