> then you read the room and go with the layer of abstraction needed.
Finding the right layer of abstraction is orthogonal to the write-speak axis. When speaking to my colleagues, I use technical jargon that no layman could understand. None of the topics are simple, or strongly abstracted. The issue of write vs. speak is more about the sentence structure, sentence length, and breadth of vocabulary.
But I generally agree that carefully crafted written language can capture and transport thoughts much, MUCH more effectively.