When you go to the cinemas... do you like to watch from 5 feet away with a 50' screen>? You need to keep things relative.... If i have a 27" 1440p 16:9 monitor or a 50 foot 1440p 16:9 cinema screen... if they are both using the same resolution / aspect ratio then i would want the EXACT same sensitivity. I would expect i am not sitting the same distance from each screen.
As a competent human being you should be able to position your head in front of your screen so that it fits in to your 'view space' perfectly. Sensitivity should not be based on SPATIAL AWARENESS, I'm sure one can understand your thumb is not larger than the empire state building even though you can block out the sun with your thumb...
The ONLY time the actual calculative sensitivity needs to be altered is if your monitor size / aspect ratio remains the same BUT the pixels per inch changes. For example a 27" 1080p 16:9 monitor vs a 27" 1440p 16:9 monitor, the latter has a higher density of pixels that will affect how the mouse moves across the desktop.