And because they're terrible at this type of optimization problem, they're getting stuck in a local minimum (the space is anything but convex), which happens to be repetitive, awful, and targeted at the largest common denominator.
Treating music as an optimization problem may not be a bad thing in itself, the issue is being unable to solve the problem properly.
Iterating endlessly on a single recipe is just not how you build a sustainable artistic business. It makes money in the near term, but it is doomed in the long term. The music labels and Hollywood will have to realize this at some point.
I presented and DJ'd on a community radio show for a few years, and had a bit of a cult following around here, however my main focus was local talent, and was decidedly not the mainstream nor even the mainstream-indie like Triple J plays. My audience was limited by that.
People don't really want to hear new things on the whole, and if they do, they want the new thing to sound like the old one.