The problem with trying to correlate people's intelligence with the things they like to consume is that 'simplicity' is relative. You think the Star Wars movies are only for simpletons? Some people think the sci-fi genre as a whole is for simpletons. There are even people who think ALL of modern cinema is for simpletons.
You can go up and down the scale of sophistication; you can go so far towards one end that you end up full circle back at the other. It all depends on your way of thinking, what you think you should do with something that you're given to consume.
Like when it comes to modern art that's just an old boot on its side or a blue square...is it for 'the simple-minded' because there's hardly anything there, and it (let's be honest) didn't take a lot of effort? Or can only those capable of complex thought ask themselves the philosophical questions required to truly enjoy such art? Is there a right answer??
I'd also like to point out that not everyone who consumes media that's generally thought of as 'more simple' only does so because "their brain needs a break" or something similar. I can't speak for other people, but my brain is always fully on and functioning even if I'm watching the Teletubbies. '_'
In fact, I like that 'simpler' media gives me more time to do my own thinking about the things I'm presented with, seeing as there's relatively less. After all, as people often forget, ADULTS make all these things. Even the most trite and basic shows, movies and books are worked on not by a roomful of toddlers, but by a variety of mature people with many different talents. There's always some stylistic choice to analyze, something where you can ask yourself 'why did they do that'?
Of course, I prefer a little more mental stimulation than what is provided by your average episode of preschool programming, but I can have at least a little fun with anything when I think about it that way.