The pinball machine industry had masterful artists that created beautiful art for decades and decades. If the artists wanted more red in a certain area, they would have added more red. If they wanted more blue, they would have added more blue. Would you honestly walk up to Paul Faris or Doug Watson and say "hey look! I made your art better by drastically over-saturating this area with a certain color!" The art was designed and printed with a certain brightness and hue of light in mind. I'm ok with LEDs that try to match this type of light while maybe perhaps appearing a tad brighter than original, but the Rainbow Puke (perfect term, by the way) really has to stop. It's making certain games look flat out ugly.
Of course I recognize that this is a subjective topic, but I think one could make an argument based on color theory that adding additional color to existing work of art tampers with the balance of the piece a majority of the time. I personally just consider it disrespectful to the artists (not saying they probably really care, but that's just my perspective on it).