The problem with McDonald's is multi-leveled. First, it takes about 10 minutes to read the damned menu. That dramatically slowed down service, and increased preparation costs. I understand that they have cut about 40% of it out, recently.
Second, the food really sucks. It is tasteless. Burger King burgers taste like they are char-broiled. That is probably just an additive, but at least it has a taste. I can't tell the difference between the McDonald burger and the styrofoam container.
Third, they have finally added some upscale burgers to their menu, like Carl's has, but they are very pricy. When people start charging around $7.00, including tax, for a upscale burger, I ditching them and going to places like Five Guys, Burgers and Fries, or Culver's.
Fourth, people are sick of burgers and want something else, like Chipotles, or Panella's.