I think the key thing to note is that it's an art project - perhaps the intention of mixing an old school style dispenser system with a high-tech currency was the intention.
Also a great way to introduce people to bitcoin. With this, users can scan the URL to their mobile (iPhone/Android), bookmark it and within a couple of minutes also send bitcoins from their mobile to friends mobile.
You're right, the main idea was to introduce people to Bitcoin in general. Right now putting in that coin, scanning the code, pasting and address and pressing the send button is the easiest way to donate to wikileaks from Germany :)
The mechanical aspect was 'decided' by the constraint of having it ready for the exhibition. Snapping a used machine of eBay and manually filling it with boxes was the only feasible way, although I started with the idea of a super fancy ATM-style machine.
