Currently the only way to get vinegar is to wait a full week for an open container of juice to go stale and ferment. Given the crazy duration to make, It would be helpful to have a secondary method of acquiring vinegar.
What if you could press sour grapes to produce 1.0L of vinegar? They're a valuable enough curio as they are, so it wouldn't really be "cheating" per se. And it would be really helpful for those moments where you're running just a little low