The dye system is pretty good at the moment but I'm sure many have dyed gear only to see it chabge parts of the outfit you didn't exactly want changed or barely dye the piece at all. Dye channels would essentially allow someone to dye multiple or each individual section of a desired piece of gear or glamor.

I'm not entirely sure on the feasibility of such an implementation, seeing as it would require going back through alot of older gear, (however the team has said they've made plans to improve the textures overtime in the future so best time would be around then I'd say) but I'd like to perhaps one day see such a system in XIV.