So, even when we get more options, people complain ;-).
Don't hit me, just kidding!

Don't dream, there won't be an option to toggle on/off the colors of the players. The game would have to load a different model or something like that, meaning having to store two models for every character, and what would be the "base" colors? How would the game know what is "normal" and what is "not lore appropriate"? Not happening in this timeline.

As mentioned above, there is already horrible immersion breaking characters in FFXIV. People who wants to embody freaks will not be multiplied by this new option. Most players want their avatars to look cool.
And personally I played Aion, nothing could hurt my eyes more than the players' avatars in that game.