No, it doesn't taste (or smell) good because it's nutritious. The cravings are a psychological reflex of remembering something you liked the taste, nutritious or not.

There's people who doesn't consider charring meat having a good odour, and that doesn't make it less nutritious. There's super tasty things which are horribly un-nutritional, or even poisonous. That goes both for smell and taste.

"The cravings are a psychological reflex of remembering something you liked the taste, nutritious or not."

Nailed it. We used to have summer dinners at my grandparents when I was a kid, complete with grilled burgers. It is, in large part, emotional.

This is specious reasoning. A whiff of cigarette smoke can trigger cravings for nicotine. That doesn't mean one is missing something essential or that its nutritious. (or that one should eat a cigarette occasionally to stay healthy ;)