I generally only think of courses as things in fancy restaurants. Sometimes I would groan because I wasn't sure how I could manage to eat a salad with heavy dressing, a giant pasta dish, and then a chocolate dessert. But even though I was worried about my stomach exploding, I always managed to eat everything and enjoy it. This was not the same thing.
The French word menu not only means "bill of fare," for which la carte is the more common term in France, but also "little"; and by its use in relation to food, we mean to suggest our sense of small offerings. The essence of French gastronomy is to have a little of several things rather than a lot of one or two.
Let us consider the French plate. It's strange for us to have a whole meal on one dish, stranger still to see any plate covered with food. The arrangement of a course in the center of a plate is part of French enjoyment. Changing plates not only compels you to concentrate on what you are enjoying at that moment, it slows the meal down, improving digestion and promoting contentment. The faster you eat, the more you'll need. If washing an extra plate seems a bother, how does it compare with getting fat?