Yes they have. We asked for Armor Dyes. We got Armor Kits that took over a year after soliciting the feedback. No one really liked the Armor Kits themselves or the price. That's why they came back again with Cosmetic Armors. We asked for something as simple as Armor Dye and they keeping making a more complex system than spimly turning the brown armor into black armor/red armor/green armor.
The braintrust at Turbine doesn't like simple. Proof can be found in that Epic Tokens would have continued to be used in all Epics after MOTU's release. Or Cannith crafting consists of two types (Greater and Lesser) 11 types of common mats, instead of just 11 mats or a flat 3 mats that consist of Arcane/Divine/Elemental. They simply don't like making things simple.
Not to mention the obsoleting or discontinuing existing systems. When's the last time stuff was added for Guilds, just as an example?