[JoshTriplett]

Backups. Reverting to old versions, such as when you observe an issue with the new version. Keeping a log of changes.

However, note that some physical manufacturing processes involve inscrutable binary files such as CAD files; you should still keep those in version control, but in the absence of specific support, you'll get slightly less value out of it (since you don't have diffs).

I have seen, however, a CAD diff view, which lets you move a slider to switch between old and new.