I think it is unfair to extend this specific experience to all personal fileservers. And TBH, I think that encrypting the storage shouldn't be done on this level. Setting up the OS that runs owncloud to have encrypted data volumes is the better way. If encryption is needed at all for taht.
Transport encryption between the various devices and the fileserver is a must, however. But going beyond that is not something I would consider to be a good thing.