IMHO, the juicer wasn't over-engineered, it was under designed. Whomever designed it wasn't given or didn't pay attention to cost constraints and didn't think hard enough about how to solve the problem in the most efficient manner.

A well designed machine would probably be more like a roller on a worm drive mounted on some stamped sheet metal. It would look totally chintzy but get the job done and cost a fraction of what the Juicero cost. It would still be a stupid product that would probably fail, but at least the hardware wouldn't cost an arm and a leg.