Almost universally, any platform that shows you data in a table format gives you the ability to download and manipulate that data through a CSV, or an excel workbook. In the RUM tool, you can search for a date range, get results on users or sessions, but can't do anything with the results besides look at them in the nice, but simple portal view. You can't count distinct entries, you can't graph anything, you can't manipulate the data.
We're a very small IT shop with no access to developer time/resources so using the API is a big ask. It really just makes sense to include some sort of "download results" button. Without this, it really hamstrings what we can use the RUM data for.