>I don't really think DVDs are "simpler to operate" except for the fact that you only need cheaper equipment

Think of it from the point of view from senior citizens. They likely already have the equipment for DVD and are used to it. That alone is "simpler to operate". Yes Bluray could often have simpler menus but that existing inertia is something that is important as well because I dont think most senior citizens are actively seeking out newer tech if they dont need to.