reading the FCOM applicable to the 'new' system, I note that one still needs an engine running to get NWS. In the 'old' ones we had always to start #2 first with the power-push - now it doesn't matter of course. That could be another reason.
eire757... to your question - yes - my experience with the 'single operator' tractor thingy was positive - smoother pushback that the towbar arrangement, and I can make smoother steering inputs than the conventional setup.