I'm surprised the opinion is controversial.

Every complaint I've seen against the 5c was that it looked unprofessional, was too colorful, or looked cheap.

People didn't buy the 5s over the 5c because it was expensive or offered more features or power. They bought it because it was the only option that looked like a phone and didn't attempt to call attention to itself as a fashion statement.

Apple banked on the lower price offering requiring further differentiation and uniqueness to sell well. In fact, it requires less differentiation and more generic appeal to be acceptable to the larger market.

They designed themselves into a tight niche, instead of opening themselves to a real market. Big mistake.