I have to agree that lots of times guys put too much emphasis on the wrong things, including exact color matches.
Some also go too far in the other direction, and generalize too much.
I agree with the rest that shape and size are probably at the top of the list.
Regarding color, I try to be in the same general ballpark colorwise as the real thing, without being obsessive about it. I figure that even if the trout can't discern the fine differences in my artificial fly coloring, they also can't discern a real insects true coloring either, but at least my offering looks to be the same shade of gray or green or purple as the real thing, without worrying about biological or anatomical details in the fish's eyes.