Since those are body parts which take colors.
Complexion comes in colors, too, but not ones well supported by ANSI colors. White, black and brown are all rendered in %normal text, and I don't even want to get into %red or %yellow options :)
I also would love to see black be a deeper shade of the %normal text so it stands out more.
I know all these things are just aesthetic, but when not overdone the little color bursts in a description really draw the eye and would make a tattoo that SHOULD stand out, actually stand out. Maybe?