This seems like a werid hangup for what is essentially a substitute for graded readers for language learners. You're not getting any of the things you mentioned going the "human" route.
No one is saying go read these stories over full blown novels. There's no complexity difference between full blown novels and most native short stories either, just length so that's not really an option.
If you could read at that level, you wouldn't be using this or the non-LLM alternative anyway.