Good point. There definitely does seem to be less protrusion in left-positioned VFs.The thing is, when you have a centered viewfinder, they are usually poping out of the camera, since every one needs that. On the rangefinder style, they are very flat (like NEX-7), because right handed people just put their eye, and that's it, the nose does not touch anything.
I also think that this might be aggravating when you add an eye detector to the rangefinder body, since it will be probably calibrated for a very short distance.