This is especially true of America where portion sizes are gigantic and people consider themselves primarily bargain-hunters rather than experience-seekers. It is amazing to me how much Americans will complain if a restaurant offers portion sizes just a little bit smaller than other restaurants in the area, even if the quality is much higher.
I suspect changing this attitude, more even than the promotion of local/organic/sustainable food production, could be the biggest social benefit of the foodie movement.
On the other hand typical American restaurants often insert sarcastic lines in their TV ads about how our portions are nothing like "French" portions -- you really get a bang for your buck when you eat here.
So it seems like there are 2 very different attitudes and 2 very different types of consumers. Both are catered to by different types of businesses.
I think the portion size has also been a hint as to how much a person should be eating. Those have been used more by the food processing industry to "mask" the caloric content of their products, rather than by consumers to modulate their food intake appropriately.