Nah- from the engineering side, it's totally trivial. Expanding the circuit or expanding the board is easy. But all of those elements mean they need to have all of the production tooling to be redone, and that is expensive.
The wire and pickup element you mentioned are production issues.
Well, I have some experience in electronics design, trouble shooting, and A/D,D/A signal processing and MIDI conversion, and I still think you oversimplify, and In fact, I would even say the production stuff would be no big deal. Not even sure if you'd have to do much, if any retooling... I'm betting it'd fit in the same box.
Also, just so you don't think I'm talking out my... ear... I have over 14 years experience working for a company the designed and built electronic equipment all in house. From concept to boxed on the shelf ready to ship... including both surface mount as well as older school through hole component technology. The only thing we didn't do in house was etch the boards we laid out. We didn't do signal processing (that part came later for me), but we did high speed communications protocols and protocol conversions, so much of it's applicable.
Conservation of hardware design is usually easy unless you're radically changing physical interconnect, because by the time you rev the product, you can get more advanced stuff and fit more cool stuff in the same form factor. Double the horsepower, double the features, but halve the hardware.
Retooling would only be for the pickup, IMHO.
But it's a moot academic point anyway. The product ain't happenin.
Anyway, FWIW.