Cravings are a bit unintuiative, from an evolutionary advantage standpoint. Why should our brains sometimes fixate on something we don't have, and drive us to distraction trying to obtain it? Even worse, why are these cravings sometimes about things which we cannot obtain - things which may not even exist?
This question is not just idle speculation - understanding cravings is a critical element to designing a product that people will want.
A key element to dissecting cravings is to first understand the role anticipation plays. We don't crave something unfamiliar - we crave something that we can bring to mind in its absence. An earmark of a craving is that it persists for a significant amount of time - as opposed to a fleeting curio. That time spent in anticipation directly impacts the strength of the craving. Building anticipation generates stronger feelings.
I have young children, and one of the more endearing/frustrating attitudes young children exhibit is a passionate defense of seemingly random statements. Children behave irrationally, but they don't comprehend how easily adults can distinguish between their truths and their lies. So children vigorously defend their lies - (probably aping bad behavior they see modeled by their parents) - even when caught red-handed in their deception.
I see this same behavior when people defend their cravings - say in anticipation of a film sequel. People will extoll the virtues of the unseen film, and defend attacks against it with a crazed vigor which you never see used to defend a film post release. (Barring some especially controversial film? Perhaps?)
The trait of craving which probably makes it the most vulnerable to ridicule is the fact that cravings, whether fulfilled or unfulfilled, tend to just stop at some point. Unlike needs or other desires, a craving which has passed doesn't make sense any more. This is perhaps the most dangerous element of cravings - because it allows unscrupulous manipulators to cause craving after craving, without fear of negative backlash.