Rather than thinking of an acoustic bass guitar as a big guitar, it seemed to me that an acoustic bass guitar should be a small contrabass. So using a cello body makes a lot of sense!
The Bace is an instrument designed for bass guitar players looking for a contrabass-inspired sound, while keeping the familiar feel of a traditional bass guitar.
The sound is probably as close to an upright bass as you can get with a 34′′ scale cello sized instrument.