I *guess* the reason is actually pretty simple.
The Kindles need to export a part of their storage via USB. Then again, Windows doesn't seem to like devices which do not contain a partition table, but directly a filesystem. Try it: take an old usb stick and mkfs.vfat /dev/sdb.
I think (assuming non-faulty memory
) that I've seen Windows accept such devices a few times, but simply not being able to use them most of the time. Windows clearly wants a partition table on a disk, even one with a single partition in it.
So there you have it. The easiest way to achieve this is to export the partition
as a drive
- and to create a partition table in the partition.