Not necessarily. They can have a target margin of X% which is completely reasonable. Then they lower X for the lower RAM options and increase X for the higher RAM options. That way more people can buy your product, as many will be fine with less RAM. And the ones that really need that much RAM will contribute more to the margins needed for R&D and marketing.
I can't believe that people are still surprised about this kind of pricing, because it's completely normal pricing strategy in almost every market. If this is greed, then I guess greed is simply wanting to be able to run a viable business, and wanting as many customers as possible to be able to afford your products. It's basic price discrimination, and personally I think it's a good thing.
I suspect when you're selling at the quantities that Apple are doing, they'll have to consider the impact their RAM pricing will have on RAM shortages. If they price the highest RAM option much cheaper, everyone will just buy that option, even if they don't need it. At those volumes, that could trigger the need to build new RAM factories, which will drive up RAM prices a lot in the short term, which is rather self-defeating.
They have to make money somehow, it means selling things for more than they pay for. They chose to make higher margins on the 16GB model than on the 8GB or less models, which is not particularly shocking.
