I really think it's a good idea. If there is one thing I can't stand in a MMORPG, or any MMO game is the fact that I can't match my colors because one piece of armor is stronger than the last piece I had on, so therefore now my colors of armor does not match. It's rather annoying not matching. I have to match everything on me in real life and when I play a game and I see my character looking like some slum out of the streets because she doesn't match, it drives me nuts! I have actually made a set of lower level armor to RP in because the armor that I wear when I am fighting does not match at all.. It really does drive me nuts and I have to agree. I really think that having a way to "apply" color to our armor would be a wonderful idea!
You can make all your armor match the chest piece. That's already in game. It's an option under the Character/equipment screen.