Yep, some gear skins come with 4 channels, but they can be just as jank because Anet applies some weird armor sheen/funky leather/cloth on some of them and the colors come out all whack which leads to an unfashionable piece.
Unless SE is literally rodeo hogtied up by their own spaghetti code, there really isn't any reason to do just 2(hopefully more down the road). They also shouldn't forget other undesirable uncolored bits on armors, need to at least dark color match the primary or secondary dye used.