I haven't played with the tool yet, but I would imagine that in certain situations (e.g. the cohort is small, or the data is not being exported from a database, or transcribed from a physical piece of paper), having a text input field on the create cohort page that allowed a list of usernames to be pasted in (e.g. from a wiki signup page) would be much more convenient than creating a csv file. 

(I imagine that once unified usernames really work, perhaps the requirement to add the project name to the end of each line could be eliminated and instead the project to produce metrics for could be selected on the "Create Analysis Report" page.)

Best regards,

Bence