Creating a compelling strategic narrative or strategic story for you business is a great thing to do.
Why?
Cause it's the story of why someone would buy what you're selling and what makes you unique and valuable in the eyes and mind of your customers.
This is the document that is the most viid and compelling piece of collateral.
Who should create it?
I would argue the marketing leader in tight collaboration with the product leader and CEO.
There's no silver bullet to creating one.
It takes time, but you need to first understand the core value the product delivers, who should be buying it, how is it different and better from the competition, what is the company's mission, and have evidence to back up your claims.
This document will manifest itself into many other assets, both shorter and longer.
A story is better than a list of facts or figures, because people remember stories, and a story is more mendable than a list.