In at least Germany, Sweden, and Austria (and most likely many other, if not all EU countries [we did it at my University in the UK]) it is a requirement by law to keep a hard copy in an archive for a number of years.
The export to .csv option contains little information, and what information is there is often not useful for the above purpose. A full detailed exam script is required.
Currently, the only way to do this is by printing each student's individual assignment, one by one. If you have many hundreds of assignments, this can be very time-consuming.
There should be an easy way to bulk export to PDF