The danger for consumers is assuming this is a zero-sum and that the converse economic goal applies to you (i.e. assuming that the consumer benefits by eating a lot or focusing on meat). I conjecture that after factoring in the economics of health and quality of life, the economic optimum for a typical buffet consumer is the same as for any other eater: to eat sparingly and in a balanced manner.
There is one other aspect about buffets: food is available quickly. This is primarily useful when traveling, if one wants to have warm food with significant cooked vegetable content (keeping in mind the aspects raised in other comment threads) without adding an hour or more to the trip.
To put it in game theory or economic terms, minimizing the buffer's utility function does not (necessarily) maximize your own utility function and vice-versa.
As a "game" the buffet has competitive and cooperative aspects - hiding some of the best stuff but still offering it to those who demand it.
I think you would want to eat nutritionally balanced, yes. But you would also want to eat the most calories possible that would stick with you long enough to skip followup meals and not exceed your ideal daily caloric intake.
I can skip breakfast and eat a really big late lunch and won't need any more food for the rest of the day until lunch the next day.
