Here are my two cents for what they are worth.........I feel the people responsible for the poor variety between the restaurants would be the chefs. I say this because I feel if the powers that be want every restaurant to have the same base ingredients (i.e. 10 oz. NY Strip, 8oz chicken breast, 8oz salmon fillet, etc.) it is up to the Exec. Chef at each park/resort/restaurant to show a little creativity and skill to make that ingredient special with the items in his pantry...........the chef needs to make the most out of what he is given to work with. Yes, you may be able to get salmon at every restaurant, but you don't have to have it served identically at every dining venue.
Just a rant from a chef who thinks the food issues could be fixed with a little creative flair from my brothers in the the WDW kitchens!!!