So I got a couple things for dyes.
Firstly, making them should give tailoring experience. Or some kind of alchemy experience if potion brewing is in the future. (Given the amount of herbs and a system for heating water already in the game, alchemy should be in the future.)
Secondly you should be able to use the dyes to change the colors of things. Like floors and walls. Got three primary colors already to work with, so apply blue to a wall and it turns blue apply yellow to the same wall and you got a green wall. Would allow for some more flair and style to building.