sounds like most people buying the new zeiss lenses are preferring the nikon mount ( zf ) over the canon mount ( ze ), why?
For a lot of reasons.
Older manual Nikors were known for their sharpness and for years were color matched through generations. They also had manual F stop settings on the lenses when other makers when to servo settings and most importantly, there was a huge range of focal lengths and specialty lenses available.
It was natural that the motion film world picked up on them. You could get a convertor to an F mount on almost any camera and tons of lens makers and third party camera repairs would build you a Nikon mount.
They were also small, lightweight and most had a 72mm front screw mount across the range.
Even to this day, some Nikon lenses are considered legendary.
I have an old Push Pull 80 to 200 zoom that we continue to use on our REDs. It's been through hell and back and is the oldest lens I actively own and use and it still is amazingly sharp.
In regards to the "backwards" focus, that depended on what you were use to and most people adapted quickly.
In fact in stills, going from Nikon to Canon made me believe Canon had it backwards.