Just because a children's story, for example, is "simple" doesn't mean it isn't inflected by human complexities.

When you're learning a language, your brain is going through a unique process of both attention to small detail and rote memorization. If you see a pattern often enough at an early stage of language learning, you'll most likely carry that with you at later stages. Even if you don't notice it at first.

Would you trust an AI to present you with accurate language patterns--speech, vernacular, etc?