As a Business Analyst, we are not there to make decisions. We are there to help the client understand the decisions they are making and provide them with the options to make the best decision.
This means a business analyst needs to understand the domain and how different changes are going to affect the domain.
Change always involves people so a business analyst needs to understand all the stakeholders involved and how they will react to the change.
A business analyst needs to understand the value that is created by all the different courses of action and who receives that value. This understanding helps the business analyst to facilitate decisions that bring the most value to stakeholders.