[sdenton4]

The only real problem I could see is if the general purpose microcontroller is significantly more power-hungry than a specialized chip, impacting the battery life of the earbuds.

On every other axis, though, it's likely a very clear win: reusable chips means cheaper units, which often translates into real resource savings (in the extreme case, it may save an entire additional factory for the custom chips, saving untold energy and effort.)