The thing that I've found as an artist is that, as one's skill grows, the management of that corresponding complexity can overtake one's creative capacity. At higher levels, the methods and structure required for competent execution are a cognitive load that crowds out other impulses. I think this is why you see a lot of older artists create works that are proficient, but repetitive, the habitual overtaking the innovative.

But I don't think this is an unavoidable trajectory. Instead, one has to cultivate "creative thinking" in the same way that they do other skills. The thing that I've found most useful are arbitrary constraints derived from things like word association games. They encourage all kinds of divergent thinking.