Ray:

I can see at least one useful purpose for colored notes.
Say I'm teaching my grade-school grandson to play bass guitar.
I put colored dots on the fretboard to match the colored notes on the staff.

He follows the staff notes by fingering where the corresponding colors are on the bass fretboard. He soon (hopefully) learns that whenever he sees (say) a blue staff note, that he needs to play a G note on the bass, and eventually the colors become unnecessary and he can remove the colored dots.

Just a thought. I have enough grandsons I should try it out <grin>.
LLOYD S