I suspect one answer might be oversampled originals then tend to look very, very good at the output resolution, for a similar reason that even on a final VHS, it's pretty easy to tell the difference between a master on 35mm film and one on a cheaper camera - even though both are far better than the VHS itself.The EX1.
It uses lots of small pixels to create a 4:4:4 image, ........... Seems like a lot of wasted tightly crammed (small) pixels to me.
Doing it this way also means a straightforward approach to processing, which can likely transform into low noise figures etc. Pixel shifting has a theoretical advantage in that it allows bigger pixels (=more light collection) and an output with greater luminance than chrominance resolution. So yes, perhaps better suited in theory if you intend recording at less than 4:4:4 anyway. But it also involves more processing, hence noise etc, which may well counteract the potential benefits.