If the Business Analyst (BA) is an architect, then think of the User Experience (UX) designer as an interior decorator.
Personas and user stories are the foundation for both fields.
User stories, done well, could solve several of the conflicts that surface once needs come across with delivery. They elevate all kinds of details (requirements) that use cases alone brush behind the couch. Understanding the people beyond the tasks they perform for the business has a great value. Some features will never be mentioned, but knowing a persona’s motivation will allow BAs to think outside of the box. For example, during an interview, one of our stakeholders expressed wanting to track performance of his employees. When we asked why, he stated that he could no longer take his employees word for how busy his warehouse was and had no way of measuring it. Here we discovered that our stakeholder wanted to track freight, not his employees (even though this one was pretty much spelled out for us).
Having a primary, concrete persona allows you to create a consistent user focused product.
"Widening your target doesn’t improve your aim.” - Alan Cooper
Find patterns in user tendencies & stakeholders characteristics. After, use a persona poster template to map out behaviors. Avoid the 'elastic user.’ Cooper puts it best, "To create a product that must satisfy a broad audience of users, logic will tell you to make it as broad in its functionality as possible to accommodate the most people. Logic is wrong.” What ends up happening is you half deliver to every different persona. Generally, if you nail the requirements of the primary user other needs will be satisfied.
No one will spell out the non-functional requirements for you.
“Any product that needs a manual to work is broken.” – Elon Musk
Sure, UX Designers and BAs are different roles in tech projects. But how different are they? Really? If the end users have a hard time with a software solution, did the BA do a good enough job? The more skills in your toolbox, the more effective you will be in future projects. This is best illustrated in a blog post by Laura Brandenburg: "We’d hold reviews with the business stakeholders, development team, project managers, and QA and painstakingly review the details of the use case alongside the user interface wireframes. Many of these discussions were essentially design discussions as we all struggled together to figure out what, how, and what’s possible all at the same time.” Would these struggles still exist if UX was an essential part of the BA’s body of knowledge? Probably not.