One of the downsides of the hidden volumes feature of TrueCrypt was that the data couldn't be actively protected from destructive overwrites - you can't plausibly deny a secret volume exists while also telling the OS not to overwrite your nonexistent volume. The solution here seems to be that all volumes are created, and if you don't use 15 secret volumes, whatever you don't use is essentially wasted space.
I suppose that is a win for data integrity, but at least with TrueCrypt most users probably didn't use the hidden volume feature, whereas I don't see why anyone would use such a wasteful file system unless they specifically needed hidden volumes. You immediately lose the plausible deniability that there isn't at least one hidden drive, and now you're getting hit over the head with a wrench until you come up with 15 passwords or pass out.