The idea is simple. With readily available parts companies could change existing USB mouse products to make buttons or a button on the mouse position sensitive.
The reason is that it would give the novice who might not be used to a penn-tablet working in Blender 3D or Gimp a lot more control. There it could be used for changing strength or size of a tool.
With such a mouse you can make the novice ( like me ) be able to control a whole lot more than just clicking. I for one would like one for when sculpting in 3D where delicate touch and flow is needed.
Maybe it could be a very cheap starting point for a transition to a proper tablet.
The idea is meant for companies who fully support the Linux effort.
In the below example I made a wooden pencil inspired mouse with a long spring loaded third button capable of detecting how much it has been pressed.
and I LOVE Blender. Here is my first 3D model of a fish.