Why did the French classical menu die out?

Answer 1

The classic French menu came in disrepute over allegations of high fat content.

While those allegations, like all generalization, were not generally correct, the more modern French cuisine takes care to control fat content, preserve vitamins and present a healthy and well-balanced diet. This is in line with most cooking methods and styles over all developed countries, were modern preparation methods, general education and awareness of health and environmental issues have grown substantially over the past 50 years.

The claim that the classic French menu died out is highly disputable though, as traditional (classic) French cooking is abundant and common in France, both in restaurants and private homes.

Traditional ingredients of high fat content, such as Foie Gras, and traditional fat-intensive preparation methods such as confit (which, ironically, does not produce an exceptionally fat dish, if prepared correctly), are found on the menu of most French and French-styled restaurants.