“Once sheet music is all digital, why not always colour-code notes?” Evidence from George L. Roger’s study on color coding music notation suggests that this would be a popular move with many people. Why? Because 65% of the people in his study preferred the colored coded notation.
Roger states:
A positive affective influence was noted for the color-coded notation when 65% of all subjects favored the color-coded notation as easier to play… (72)
Therefore, you could make an argument that since people like it better, and it makes the music easier to read, why not adopt it for everyone?