I think it has more to do with the overall scheme than just the appliance color. Like I said, it won't be long before granite and stainless look dated. It won't be necessarily one or the other, but the combination. And it has not much to do with the color or design, but more to do with the current trend and what's popular now.
Like steelreign mentioned marigold and puke green used to be the hotness. Now you would look at that and laugh. You never know when that shite will make a comeback though.
Even, though I don't see that happening anytime soon. Its kind of like people don't want their homes looking like their parents or grandparents home.