Who said so? The colors in TOS are so vibrant and gorgeous to look at. I don't find them distracting at all. On the other hand I tried recently to watch TNG and DS9 on Netflix but the colors/lighting are so depressingly bland/dark that I kept losing interests and falling asleep. However I don't understand why Kirk was put in those green shirts especially that wraparound shirt. That color doesn't convey a lot of gravitas or authority.