Roy's name at one time was "ROY G. BIV", because it used to be common to call the region between blue and violet "indigo". In modern usage, indigo is not usually distinguished as a separate color in the visible spectrum; thus Roy no longer has any vowels in his last name.
The normal human eye is sensitive to the full range of the visible spectrum, but not equally sensitive. The eye is more sensitive to the yellow and green regions in the center, with the sensitivity dropping off as the wavelength decreases toward the red or increases toward the violet.
The Sun produces its primary light output in the yellow portion of the spectrum. Thus, it is probably not suprising that life evolving under the influence of that Sun developed eyes that are sensitive to yellow light.