I know Autocad support high-resolution displays images for the button icons. Revit could have the same thing and show a high-resolution icons when the user have a high-resolution displays.
I copy some similar Icons from Autocad and put inside Revit just to compare with the default icons from Revit.

In the image: The screen scale is 200%, on the left the standard Revit icons appear bluer and on the right the Autocad icons looks sharp.
Here some reference how that could be done with plugins inside Revit.