Might strike some as a ridiculous statement but that was a factor for me deciding to go 1DX2.
Now that there really is no camera that ticks all the boxes and given the 1DX2 is relatively low resolution, it seems nuts that certain features should only be available in that camera (cost of course is going to be a factor, assuming the feature is expensive to implement).
With mirrorless, the AF points could be any color, but with so many of them, the subject would not be viewable. They show them as white which is easy to see and they turn to green when in focus, but no more are all the AF points continuously displayed, and what is displayed is not the AF point, but a general area covering hundreds of AF points. 5,665 points is just not something I'd want to see in my viewfinder, and the new higher mp cameras may have a lot more.
With my EOS R, I tend to use a single or expanded AF point and it is continuously displayed in white, which works great for me.