FIVR is the most obvious main use for this I've been following this stuff since the 00s, "The Singularity is Near" is basically my bible. Back in my audiophile days I used to dream about something like this for music, so it's interesting to see him mention that use. With this you'll finally be able to actually perceive the extra frequencies and achieve sound quality impossible on speakers.
In the near future this could be a way to produce accurate and realistic sound for HMD based VR. Still, getting a brain implant for something like audio would be very drastic and will likely stay a niche thing.
BCI implants will only ever become mainstream when full-immersion virtual reality is possible.