This is something I'm able to carefully concur with even if at the end it sounds offensive to someone. As long as I'm involved in AI development it seems like neural networks used for prediction and pattern recognition work the same way as our "still human" brain (and some of them modeled directly after neocortex) and I'm utterly upset about what we may face in a very near future. Living Fossil, you're absolutely right about the pattern and some expected model mutation. So how to force a mutation - introduce some distortive force and in AI it's usually represented by some external artifically created noise that is a perfect example for the social/musical/political/etc environment. The distortion is essential to the quality of the model for the sake of prediction capabilities because following the same pattern eventually leads to the model degradation and lack of aiblities to react to slight changes in the environment. Actually among the others there is another method of improving the predictions called "ensembles" by combining different model types together even if alone they don't produce good results. Just think about how it again corresponds to human collaboration.For me, an effective method to judge "epigonal" pieces relies in comparing them to the "originals". (And sometimes, it's the shortfalls of epigonal pieces that improve my respect for the "originals")
There is a huge existing knowledge about musical hermeneutics. These tools can help you to analyse the core of the inner network of a specific piece of music in order to approach the specific "substance". To put it in an overly simplified way: relevant works always use models to a certain extent. But at a specific point, the model is distorted/modified. What follows, is a stringent justification for the inconsequence. And the justification carries the "message".
You find this pattern in every substantial piece of Bach, Mozart, Beethoven, etc, etc, etc.
I don't hear any of this in AD's exercises.
I hear this pattern sometimes in music that doesn't represent my personal preferences - e.g. Rap music; hip hop etc etc.
So i guess, while it's impossible to make clear distinctions, there are parameters one can approach by listening carefullly...
Mutation, or "message" is good, following or layering over the same pattern again and again does not improve its quality and leads to conversion of the "brain" to a sort of finite-state machine what makes it amazingly vulnerable to unexpected influences or even slight change in the input data.
And yes, it happens in any music style.