How can AI be the amazing thing you say it is, but also too stupid to understand unless you get really good at communicating. Wouldn't better AI just mean it understands your ramblings better?

It's fine if the "rambling" is logically coherent. So the communication ability isn't really about expressing your thoughts eloquently, but just effectively and clearly. Run on sentences and train of thought is fine as long as you are saying something meaningful. But no AI will be able to read your mind and know exactly what you mean by "make really cool looking website, not lame please, also nice colors, not boring". Declarative programming through natural language will become incredibly powerful.

Many humans are great at their expertise but bad at communicating. How?