I suspect that is a huge factor, indeed. I often see people using bad mice, with uncomfortable shape, bad buttons, bad sensitivity plus often acceleration enabled. Then on top of that, people are putting mouse in some weird locations, like a narrow slit shelf, or far away from the keyboard (because they have a bad sensitivity configured in part). Or even no mouse and just use trackpad (even the superb one like in Macbooks). Of course GUI would feel clunky that way.