Some foods aim at pleasing our palate, others go for our heart; macaroni and cheese bypasses all that and goes straight for some undiscovered part of our primitive monkey brain. Don't ask me how we monkeys developed a deep-seated biological need for the stuff, but lurking somewhere in our heads is the Platonic form of macaroni and cheese that we all strive for.
I suspect that it has something to do with the marketing people; commercials for various boxed products look so perfect that the disappointment when you actually taste one of said products is profound. This dissonance creates some sort of Freudian phenomenon wherein we form an intense relationship with our inner macaroni and cheese.
Consider the recipe in the NYTimes (the article's expired, so I'm linking instead to Slate's review of the recipe) earlier this year that was one of the most emailed articles of that week. It's clear that people yearn for something more than the macaroni and cheese that they've got.
This is where I come in, with a little help from Patrick O'Connell's Refined American Cuisine. Don't worry! This is not a frou-frou gourmet version; okay, well, yes it is, but if you leave off the shaved white truffle and the parmesan lace basket from the presentation, what you have left is the exact creamy, dreamy macaroni and cheese that you crave.