A really effective prompt is created by developing an accurate “mental model” of the model, understanding what tools it does and doesn’t have access to, what gives it effective direction and what leads it astray

Otherwise known as empathy

It's a bit different though; the soft skills you mention are usually realtime or a chore that people don't like doing (writing down specifications / requirements), whereas "prompt engineering" puts people in their problem solving mental mode not dissimilar to writing code.

(assumption / personal theory)