I am not suggesting that a designer should necessarily aim at a varied public - there are niche products and genres, and that´s fine. But you will notice that most examples have been quite successfull in both short and long terms. Here they are:
TV: The Simpsons
The longest running animation in history is capable to please children and adults of all age. It is no secret that part of its success is due to its allusions and references to works and characters that should be familiar only to a parcel of the audience. Still, it also has a very strong, straightforward, comic verve, that does not depends on sophisticated levels of literacy and can please anybody.
Literature: George Orwell´s Animal Farm
Again, a very clear piece of work that can be read and enjoyed by children, but that also is very interesting to adults for its political message, which is about Orwell´s strong critical view on the communist regime.
(It seems there´s a film adaptation)
Music: The Beatles
Or even just Sargeant Pepper´s Lonely Hearts Club Band, for that matter. The Beatles successfull fusion between catchy pop tunes, avant-gard art and classical music (this one, thanks a lot in part to producer George Martin) took rock music to a new degree, earning even more respect and credibility for their work. In a single album, sometimes in a single song, they could add elements that would please the ears of people with different musical background and taste.
Its front page is still a single form line with two buttons. However, in the hands of experienced users it can trasform into a all-in-one online center.
In the end, it seems that it all comes to what the reader/player/listener chooses to pay attention to. It´s about giving not only variety, but depth. Taking care of 'casual' and 'core', to bring back these terms.
Ok, so what games would you say that have this kind of quality? Well, I would start a list with Sensible World of Soccer. Very simple to play (one button!), and several levels of micro-management that could be safely ignored, if so the player wished to. What games would you add to the list?