When people make purchasing decisions, pricing models that are too complex make them less likely to purchase. If it's too confusing to figure out whether something is a good deal or not, we generally tend to just assume it's a bad deal. See http://ideas.repec.org/p/ags/ualbsp/24093.html (Choice Environment, Market Complexity and Consumer Behavior: A Theoretical and Empirical Approach for Incorporating Decision Complexity into Models of Consumer Choice), for example.