I mean, we literally have an aesthetician in the game, I'm pretty sure hair dye exists in Eorzea so 'realism' was already thrown out the window.
That said, if altering/adding colors in the CC is not much different than adding stuff like the WoD stubble *cough* or Highlander eyebrows *cough*, which we already know the devs had issues with, I'd put this in a "it's not impossible, but don't get your hopes up" category /shrug