[vple]

I think good writing is more about the higher level: effectively communicating a point. Mechanical components, such as grammar, are important but don't help express ideas.

As a tangent, I think a lot of the soft influence you mention requires effective communication, not effective writing. In my experience, it's important to understand the context and information that others are working under/with, and to make sure that relevant information makes its way to people who need it.