Qualitative information helps to make applications more accessible because it bridges the gap between the real world that we all live in and the world of the application. The world of an application is a specific place with its own data and its own rules. It can be difficult to understand an app unless you are familiar with the numbers it displays. Qualitative information helps give context as to what part of the real world an app is analyzing and why.
You can use more technically savvy solutions to help dynamically narrate what is happening within a data set, or you can go low-tech and simply write a paragraph of text giving context to a data set, or to a particular chart, etc. However you get there, the key is to help users make the connection between the world of the app and the world they are already familiar with. Data literacy is increased through qualitative information. Dr. Brené Brown said that “stories are just data with soul” and the best way your quantitative data apps will get a soul is by including qualitative information.