the way we perceive color isn't the same way wavelengths work though. we practice amounts of specific wavelengths, not the wavelength themselves. which means that we perceive colors that don't have a wavelength, like pink. which only exist in our perception. so any attempt at improving ROYGBIV is as arbitrary as Newton's attempt. Fuck, we know there's also infrared in there, so only improvement would be irROTGBIVuv.