When you are mapping fields for import, it would expedite the process if the mapping headers would automatically populate based on the names provided in the uploaded CSV file.
For example, the column header in your CSV for "Email" would automatically map to the signup email field. The dropdown menu could then be manually adjusted by the user if need be.
This is something we will consider but does not have a timeline at the moment.
However we are paying close attention to the most popular suggestions so please share and encourage others to follow and comment!