I’m always reading your interesting thoughts, but have to be a bit picky regarding the medical imaging claims.
Even today CT and MRT scans are displayed as black and white images on special monitors, which can “properly” display all necessary levels of gray. That being said, you can find colored images, e.g. via functional MRT images, where the color might denote the flow direction or speed of the liquid (blood) in the vessel. While color codes can be helpful (as seen in the fMRT example) often a grayscale image (on a medical monitor) is more beneficial and not necessarily limited by the compute power your machine has. 
The most important aspect is what exactly do you want and need to see in the image.
Medical software usually comes with some presets using special “windows” to display certain tissue classes. E.g. if you are only interested in the lungs, you would select the “lungs window” so that the proper voxel intensities will be scaled to the full monitor range.