I seen that done in AION where you can buy dyes from vendors or gather them or have them as special drops and dye your armor.
I saw an improved version of that in GW2, where you would unlock colors for your character and then be able to from the 'profile' page (or whatever page you see your armor etc) select each part of the armor (main part/base /secondary layer/third layer) and select the color which you have had to unlock prior to being able to use. (a whole lot of content there. quests, bosses, grinds to unlock colors)
Cosmetics in game really matter. I mean that's why SE spent so much time trying to make the game so beautiful and eye pleasing.![]()