well, all the bits about the merits of HD aside, you would definitely see an advantage to having more colors. It isn't just an issue of how many colors you see at one time, but about subtlty and blending of different colors. For instance, in human skin, it's very easy to portray it all as one flat color... like tan, or peach or brown, whatever. however, human skin is not monochrome and it actually has translucent areas where blues, greens, reds, etc show through. Having more bits to play with allows the TV/monitor to be better equiped to portray all that subtlty and make a more believable and life like image. That's why you want more colors.