If Apple had kept the 5 around but knocked the price $100 would you say it's too expensive for what it is? Or is the 5C too expensive purely because the case is plastic and not aluminum?
True, but in all things, perception is everything.
If Apple had kept it's previous sales model and just made the 5 the intermediate model and the 4S the budget model no one would be focusing on iPhone 5 sales & it probably would have higher sales #s than the 5C because it appeals to a broader base.
Apple's (Tim Cook's) mistake is it (he) didn't really understand who the 5C customer @ the set price point would be with it's colored plastic back -- mostly parents buying for their young daughters dying for a lime green or sky blue phone, which is a very small universe compared to all iPhone buyers.