I've never required NWS to maintain directional control at speeds where the flying controls are still effective (down to 50-60kts) in any x-wind conditions - I honestly don't know what's different about the J, although I am aware you have slightly more restrictive x-wind limits.
I do, however, accept your point re 'overall control' for commanders, however NWS is not even necessary for taxying - I remember taxying the ac quite successfully from the RHS using diff pwr. I know that diff braking is regarded as a no-no, however you still can use it in an emergency - it's all you'd have left in the case of a double engine failure on the utility side.
The fact that the fleet's copilots are considered 'unfit' to operate from the LHS is, I believe, our own fault - primarily because we refuse to train them to do so, but also, if some people's assertions are true, because we accept too low an output standard from the training system. We will get, at the end of the day, what we ask for. But I suspect that the first reason is the more accurate one. That, and the way co's are traditionally viewed in the AT world.
16B