Years ago my employer used Restaurant Associates as a food provider. RA had about 3 levels of food: gourmet, healthy and nutritious and salty and fatty. Among the minorities, no one but no one would touch the healthy food. They all gravitated towards the junk food. So the company decided to ditch the healthy food because it was a big money loser.
So, it's possible that McD’s just couldn't get rid of the healthy stuff. You can lead a horse to water...
There's a book I just started to read SALT, SUGAR, FAT by Michael Moss (Random House 2013). Its subtitle is "how the food giants hooked us". It's about how the food processors are deliberately poisoning us by hooking us with their unhealthy processing and additives.
That's why I state that as people begin to catch on, some do change their eating habits. Knowledge of food is improving, and as a result of demand it's actually getting easier to find pure foods.