> For the Original Series, the producers were just starting to explore color television and they used the whole pallette. More that the producers had to deal w

> For the Original Series, the producers were just starting to explore color television and they used the whole pallette. More that the producers had to deal with that fact a significant chunk of the audience only had black and white TVs. Even on color TVs the broadcast would crush colors. So they had to use bright colors that would differentiate characters despite being the same "uniform". Look at The Cage, all the characters had the same color uniform so everyone sort of blended together except Number One. Shatner and crew were much easier to differentiate in black and white, especially when red shirts beamed down with the principal cast.