Funny I read the whole thing thinking that this is like The Language Instinct by Pinker and then at the end saw it was by him. That explains why nothing but one point in it was new to me.

The point that did spark my interest was that it's not rules that are important but expressing yourself as a writer (or speaker), which most people are poor at.

Pinker is good, Christopher Hitchens was good, George Orwell was excellent at condensing ideas down into clear, lucid pros. Our own Dijkstra is probably admired mostly for his ability to write so clearly regardless of the topic. Hacker News's Paul Graham's success as an author of articles seems to me to be 80% his writing abilities and 20% actual valuable ideas.

That comes down to the really important point for me. It doesn't matter how good your ideas are if you can't communicate them, they'll just sit in the shed propping up cobwebs. You may get lucky and someone else does it for you. If there's a "one thing" that language teaching efforts should be focused on, it's getting your point across effectively.