The whole idea of the USB mouse was to reduce the number of cables plugged into the back of your system and so that they could be longer. (Hum.. so they can be plugged into the front?) The theory Micro$oft pushed was that you would have one USB cable out the back to the USB keyboard, and one out of the keyboard to the mouse, and one out of the mouse (oops! can't move the mouse with two cables). OK, one out of the keyboard to the USB ZIP drive and then one to the mouse.
Of course no one wanted the expense and problems of putting the repeater hardware in "their" attachment to allow the daisy chaining of USB devices....
Of course when you try to run all of those devices through one connection, they take too much power and you need a powered USP splitter, which adds another power cable....
The only advantage of USB keyboards or mice (other than marketing cool) is you can use longer cables. The data rate from such devices is way slow and a faster interface buys you nothing.
And of course USB keyboards and mice don't usually work in DOS unless the BIOS supports them.
