I've wondered that, myself. Maybe the trend is shifting to lighter cooking (I think some of the family restaurant chains had a reputation for perhaps more fat and sodium in the cooking). But I still think there is room for a variety of reasonably-priced family restaurants (serving traditional dinner meals).
Some people may be more health conscious while at home. But when they go out, they might want some comfort food like a pot roast or turkey dinner, with mashed potatoes, vegetables. gravy. rolls and butter.
I like places that give you generous portions, so that you end up taking home the equivalent of a 2nd meal to heat up in the microwave, the next day!