I think he means the diameter of the wheel is too large. That is the distance from one side of the wheel to the other at its largest point. Some people are larger and have trouble sliding their thighs under the larger diameter steering wheel when getting in and out of the car...that's one reason they may seek a change. Another reason is that with power steering, a smaller diameter wheel would make the car more responsive, less movement of the wheel results in greater movement of the steering shaft, without being significantly more difficult to steer.
For some people, originality is not a big issue, and of course, there's always that distinction between original and correct. I'm not sure exactly which you meant.