CFM: When flyfishing for salmon/steelhead the fly is usually fished as deep as possible to get the fly to pass infront on the fish. When practicing the wet fly swing, the fly is pulled sideways infront of the fish most of the time when the fish is along the bottom. I do realise that when dry fly fishing the color dose not matter as much but many trout flyfishermen could tell you that when trying to "match the hatch" color, and well size, is everything.

But kinda like you said, when flyfishing for steelhead the fly patter/color 70% of the time has more to do with pleasing the fisherman and not the fish.