Dearest Chief,
This is indeed a complicated question. And yes, oftentimes the question is asked at an awkward moment, like after a healthy bowel movement, or in the throes of looking at online, hockey message boards. Perhaps it's because they would like a framework, perhaps it's because they honestly want to please you, perhaps it's just a question, like some kind of genetic mutation, that appears in generation after generation of females. However, I think it points to a different idea, that sometimes women don't want to think about what to have for dinner.
If a woman has cooked dinner every night for days, months, years, the dinner-cooking, thinking about recipes and menus part of her brain becomes enflamed. That part of the brain is tired and weary and uninterested in thinking about what to cook for dinner. She would probably rather be doing ten bazillion other things than considering dinner options. And probably doesn't much want to cook dinner either. Menu fatigue, it's a real problem.
Having the person being asked "what's for dinner" cook dinner is a good thing. Also good: take out. Also good: going out for dinner. Also good: candy for dinner.
Eat well, my friend.
Hungrily,
Mule