I recently had a problem connecting and reading a USB device (Garmin Forerunner).

It took me about 8 hours to find and fix the problem, all because of some
insane change in the 15 kernel.

As far as I can tell, when you connect a usb device it is, essentially,
mount as unreadable. In /sys/bus/usb/drivers/usb-storage there are
two flags, bind/unbind. It seems that bind is the default option
which is unreadable. Under bind, I think, only device specific access
is available. In order to read your device as normal usb you have
to unlock (unbind) the device.

Here is how you do that:

tail dmesg and find where the device is mounted. It will be mounted
as ttyUSB#. That is the device specific mode. You will see a line
that looks like this:

garmin_gps 1-5:1.0: Garmin GPS usb/tty converter detected
^^^^^^^^
You need to pull the string following the device name,
(marked by the ^^stuff) and put it into this command:

echo -n "1-5:1.0" > /sys/bus/usb/drivers/usb-storage/unbind
^^^^^^^
After that you can read the device as whatever usb device it becomes.

It seems to me that when a system change is made, the default
should be that existing uses of the system should be grandfathered
in, and one should have to do something extra to access the new
feature.

I other words, the default should be the other way.