Having libusb 1.0 + libusb-compat is basically having two separate
versions of the libusb codebase.
The point of continuing with libusb 0.1 is to avoid the bugs introduced
by the libusb-compat library. Of course libusb 0.1 is full of bugs, but
at least we don't have new bugs breaking existing packages.
Yes, and they had to solve bugs. OTOH most bugs might have been solved
either on the libusb side or on the side of the softwares using it.
Anyway now that the upstream situation of libusb 1.0 has been solved,
libusb 0.1 should just die. Up to know I have opened a few bugs to get
some packages switched to libusb 1.0, but I plan to be more active in
forcing packages to switch to libusb 1.0 after the jessie release, so
that it can be removed for jessie + 1.