Great concept, but it's a bit ahead of it's time. We'll get there, but consumer-grade 3d printing is nowhere near unattended operation like this.

Stereolithography maybe, but additive 3d printing tech like the one shown in this video suffers from all sorts of issues requiring operator assistance - like the object unsticking from the build plate, and the head needing frequent cleaning. Unless this "vending machine" is manned, I doubt it could be useful/successful until technology improves.