I understand the reasoning behind shifting to prix fixe (especially in lieu of the dessert/drinks issue as discussed above) but it's bad for consumers. A prix fixe menu generally offers much less value to diners, either because they don't want and thus don't order the more expensive items necessary to make the pricing work, or because they just don't want that much food in general. I almost never want a meal with a soup/appetizer, an entree, and a dessert, but with prix fixe you are paying for those items regardless.
That's not to say there aren't instances where prix fixe is a good value (I will always remember an incredible prix fixe meal I had in a small town outside Barcelona), but on average it is not. It's probably even worse at Disney since the overall food quality isn't especially great, even at places like the California Grill.