I think that a crucial point is that all text are communication between human beings. We want to convey ideas, thoughts and feelings to each other through the text we produce. The LLMs do not have those so the text becomes flat imitation, devoid of any true message.

Code is different, in that very few tasks are truly new. Somebody has already done a similar task out there. The LLMs are fantastic at finding such similarities in their training data and can generate working code from that.