From an article on watches by Rob Walker in the NY Times:

Sometimes the product element that’s most useful in signaling identity is something “afunctional”.

Counterfunctionality is precisely what makes such things effective identity markers. … “So to do the opposite (of the intended value) is a good way to separate yourself from the masses.”

Some products are inseparable from the identity they confer on the user. They are markers for who we are, they confer status or a meaning about our selves. Even commodity goods can confer an identity by the specific choice of products we make. This status and identity is for many product categories the result of the product’s brand image, created by the company or the user by their use of the product. While companies can only hope that the product is used as intended once the product is in a user’s hands, a company that intentionally creates a product that is counterfunctional to the typical use of the product instantly separates it from the pack.

Obviously not all companies cannot use this technique to differentiate their products, but the key is to note that functionality and rationality are not everything.