Marketing is not about logic. Anything that degrades the perceived value of a luxury product sold at high margins is not good for your business. You never do anything remind a customer that a product is not worth what they are paying for it.
Just look at any of the most successful luxury goods manufacturers. For example, I was recently at a baby goods store that frequently provides discount coupons that can be applied to most all things. The coupons however, have a long list of excluded brands at the bottom. On inquiring, this is not because of any policy explicitly sought by the store, but because many of the luxury goods manufacturers actually prohibit sellers from offering their items at a discount. I actually had one store owner call over angrily to a competitor when he had heard they were offering discounts on a prohibited item, because she knew the manufacturer prohibited the discount from being offered by the other business. High end brands often don't want their brand subverted by having it associated with variable or cheaper pricing -- and usually for good reason. Their customers are not of the type who want to spend a lot of time shopping around for the cheapest price on their items, yet at the same time they don't want to be disappointed that some yokel just bought the same product they spend $300 on for 1/2 the price somewhere else where they were too busy to check. Sorry, that's just human nature.
Likewise, an Apple customer doesn't want to shop in 10 different stores to find the cheapest price. They just want to walk into an Apple store, a Verizon store, a Sprint store, BestBuy, doesn't matter which one, buy the phone, and know that it is the best price they can get. Having to shop around for the cheapest price only makes them feel like there is a game that the have to play, and it makes the shopping experience unpleasant.
Apple is in fact a luxury goods manufacturer. After all, pretty much the only thing that differentiates an iPhone from a cheaper android phone is fashion and minor issues related to ease of use. Functionally, they are both capable of the same sorts of things. It's marketing 101. Steve Jobs knew it well and I have to keep my fingers crossed that it's not less appreciated by current management.