The answer to that is basically a wall coming up between the artist and the patron/customer. In the old times, the patron could tell the artists directly what they wanted, and the artists would know that they would have to please their patrons or they weren’t getting paid.
So by the logic of today’s artists, it should have been the dark ages. Artists were forced to “sell out” and “stifle” their “creativity”, with “drek to please the masses”. Drek like the Mona Lisa, The Sistine Chapel, David, the royal portraits by Hanz Holbein the Elder, the plays of Shakespeare, and many of the greatest symphonies ever. This is because the artists didn’t try to be “creative”, but did the best work they could within the parameters of their commissions. And it was damn good work.
What happened? Well there could be many causes, but artists basically found ways to just listen to people who thought like themselves (even if they didn’t always agree), and not to anyone else.
Thus entertainment turned into closed circles of just the artists, associates, people in dedicated press, and the most vocal fans. These kids of circles existed for other fields, and the same problems came from that.
Basically, anyone outside the field circles would count as the mainstream for that field, and the more support those fields got outside their circles, the better those fields would do.
These closed circles are basically the worst thing to happen to entertainment in general. Not only do they make works increasingly repulsive to their fans (thus shrinking the circles even further), they are resistant to anything that appeals to the mainstream, and even if something is too successful to ignore, they miss the point of why it’s successful, like how Star Wars was supposedly successful just because of the spectacle (because a lot of people in the movie circle didn’t find any appeal in it other than the spectacle, so they stupidly assumed that was what the mainstream liked about it), so blockbuster films have been increasingly about spectacle above story, when Star Wars was actually a strong mixture of both.
Now I like the Transformers films (well the second one was a disappointment for me), but I know they are far from perfect, and it’s sad when the third film has one of the stronger stories compared to many of the other blockbuster films this year.
When the circles close enough, we get major acts of stupidity, like Other M, or the “One More Day” event with Spider-Man (I know you don’t follow comics, but I really recommend you look that up just to see how ridiculous it is).
Also, many entertainment works today about those artists in the past are revisions claiming these artists were gifted with some kind of blessing of creativity. They might think the Mona Lisa was some kind of vision Leonardo had, instead of him just doing the old timey equivalent of a Sears Studio portrait.
There used to be this thing, in video games, called the Pursuit of Quaility. It has now been replaced with the Pursuit of Creativity. I don’t want ‘creative’ games. I want quality video games. Show me something the audience says is ‘mediocre’, and I will show you something the maker thought was ‘creative’.