"I'm the audience's representative on earth." - Michael Caine
Telling a story is an action of communication - it implies both a teller and a listener. In theater, there's an audience of tens or hundreds or tens of hundreds of listeners. Knowing who those listeners are is an important part of storytelling. This is the same reason that I always thought I was really funny till I moved to Pittsburgh, and then I became solidly middle-of-the-road. I just knew how to work my hometown of Redmond a little better.
Successful shows, movies, and television series know who they're trying to appeal to and then appeal to them really really well. There's a lot of nuance that goes into this - for instance I personally think it's best when shows build the "appeal" characteristics into the plot and the characters in a way that makes sense. Pandering to the audience in an obvious way can quickly become insulting and can really take people out of the action. Yet without appeal, who will come to hear your story?
The relationship between teller and listener is everywhere, and it's one of the most interesting artistic relationships to observe. Here are two examples of stories that were clearly aware of audience-appeal:
1) Star Trek (2009) - This is a great example to start with because it is so successful. The film-makers decided to create an updated, modern, exciting Star Trek story for one simple reason: money. And to make the most money possible, they needed to make a movie that was exciting and riddled with explosions - because that is the standard to which action movies are held these days - without offending the long-standing Star Trek fanbase - because that is the standard to which science-fiction is held. Mike Stoklasa goes into this in more detail in his video review of the movie, and explains it very well, so I'd recommend checking that out. In summary though, the movie is successful because they built a story that could incorporate an action-based plot into a recognizably Trekkie world, all without compromising the fidelity of the characters.
2) Kyle XY (2006 - 2009) - This is a great example to follow with because it's by and large so unsuccessful. Kyle XY was an ABC Family show that wanted so badly to be a creation-of-a-superhero story, but the show-runners knew their audience consisted of - well - people who watch ABC Family. The ABC Family-isms are shoehorned awkwardly into otherwise compelling conspiracy-unraveling-heroics. Kyle XY was eventually canceled due to a ratings drop… when it was out-paced in the ratings by The Secret Life of the American Teenager, recently renewed for its fifth season. If that's your competition, and your competition is winning, you may be playing the wrong sport. (Disclaimer: I have never watched The Secret Life of the American Teenager, and it may be that the details of the titular teenager's secret life are of a truly captivating nature. Nonetheless, I think it's indicative that poor Kyle might have found a better home on some other network.) That's not to say that you can't make a superhero story with strong family values, but something about it rang false on Kyle XY.
I like using TV and movies as examples because people can more easily find information about a TV show or movie than they can in regards to a specific production of a particular play, but of course the same rules hold true for theater. An experimental Boalian revolution-play may not be the best thing to take around to local nursing homes, nor is Spring Awakening likely to be well-received at a children's theater. I mean, duh. But this can get tricky. Shakespeare is fairly well known (depending on the play), and if you're doing Hamlet you can bet that lots of people in the theater have seen it before. They'll probably be looking forward to certain parts - the famous "To be or not to be," speech, the ghost of Hamlet's father, the fencing - but if you cut out everything else and hammed up those bits, people would leave disappointed. Great moments in theater, defining moments, moments that audiences crave… these moments are earned. And that is the essential art of audience-appeal. As artists, we cannot just give the audience what they want. On some level we should make them work for it, even as we work for it.
So when we ask ourselves what the audience wants, we should also be testing them, stringing them along with just enough care to never lose them, asking: "How badly do you want it?"