The Ongoing Issue with Xaela Scale Coloration

[Absurdity]

It wouldn't be that hard to do seeing as we already have an entire system for applying different colors to an object in the game with multi-dyes. Average Items themselves in the game actually have up to 16 dye channels regularly, so enabling two of them for the body is well within the abilities of the game engine.

It's not that simple.
Skin textures use a different shader than gear and monsters do, one that uses the data within the textures for different purposes and consequently achieves a different look. They don't have dye channels, or even colorset files for that matter.
I'm not knowledgeable enough about the technical aspect to tell you exactly how they differ, but you can see it just from looking at the textures themselves.
The skin shader lacks the index map that all gear uses since 7.0, and instead of a colorset file it uses a diffuse map to get it's base skin color.