Out of curiosity... I take it this physical wallet isn't intended to be exchanged like currency?  But rather, it's designed to be a wallet to store incoming funds until such time as you wish to transfer these funds into a secure address?

In which case what's the point of it being tamper proof?  You can't use it as a medium of exchange anyways so there's no point in a tamper-proof private key.  If someone steals the wallet they can just steal the funds in it by opening the wallet anyways.  I guess this protects against someone finding it and writing down the key and leaving it where they found it, or photographic it, then?  But you can just leave the private key at home in a safety deposit box and carry around the QR code for the public address.

I can't imagine a scenario where the average person would need a wallet that can accept an unlimited number of coins until such time as you want to buy something with it, which you can only do once and only with certain technical knowledge (I'm thinking of the change, here) after which it's useless and you need a new one.

A tamper-proof private key is only useful when you want to use it as a medium of exchange, which this thing can't be used as since anyone can print off any nonsense private key they want to on the private key slot before they seal it off.