I mean, that’s how it was retconned, but it was originally just so viewers could tell if it was the good guys or bad guys shooting. Just like there were only supposed to be blue (good guys) and red (bad guys) lightsabers. As the Star Wars universe and lore expanded, things got retconned and added/changed/removed, and it’s still happening with the new stuff that comes out. Isn’t world-shaping neat?