Its fast, easy and cheap to prototype cases using that notched plywood.
You are right, of course, that it cannot be sanitized or disinfected. Good point.
The developers spent their time on the core product proving it works. Once the innards and their configuration are finalized, they can package it up in a nice 3D printed shell case.
Quite true. The wood case looks kinda cool IMO, even though it's not practical.