I've had hardware failures in the past with other game consoles, resulting in a complete lost of all the game save data I hadn't backed up on external storage.
Since then I've taken the habit of backing up all my games' save data regularly but with the Wii U this appears to be impossible to accomplish in a practical manner. I have no interest in purchasing an external USB Harddrive, format it for my Wii U exclusively then use it strictly for a few MB of save data which does not guarantee my data will be recoverable should my Wii U suffers a hardware failure since the Drive is formatted only for that specific Wii U.
Can't we simply use an SD card or USB thumbdrive to back up save data?