The Wi-Drive is one of those accessories that is not perfect thanks to the ridiculous restrictions imposed by Jobs to Apple's products. This accessory is an external SSD that allows you to share information with your iPad or iPhone. In this way you do not have to use the space in your iPad with movies and other files that you can easily access via WiFi from the Wi-Drive. Why is not perfect? Because thanks to Apple's restrictions you cannot copy files from your iPad to this device.
This is part of the legacy left behind by Jobs. These cases make me believe that in the same amount that Jobs contributed in the technology progress, he is also responsible for making this progress slower.