The problem with 200Hz TV's is that it is using interpolation to add frames [sort of upscaling].
http://en.wikipedia.org/wiki/Interpolation

These things have problems,mainly because you can't really add information if it was never there,which 200Hz & 100Hz screens try to do.
It helps reduce judder,but is dependent on the source material on how successful it appears,rapidly moving objects and fine detail can still cause these systems problems & fine detail to be masked.

Never having seen RealD shown on one of these 200Hz screens but having an educated guess,I would think that since the 3D system uses quickly flashing alternating images spaced apart [binocular disparity for the tech minded],the 200Hz processing would confuse the 3D image,making it blurry when that 3D imaged moved about the screen.
Where's standard 50Hz or 60Hz native refresh rate would keep this edge blurring to a minimum.

I could be wrong,but I don't think I am.