Lets say a user wants to import the QA_Contacts field from a Bugzilla instance. As this field cannot yet be imported as per this feature request: https://ecosystem.atlassian.net/browse/JIM-533

So the logical thing to do is to import the field separately via CSV import. The problem here is that the Updated field of the issue will be overwritten with the latest date. This is a big problem for customers who wants to preserve historical data on older, closed tickets.

Even if you manually specify the Updated field to a column in the CSV file, the CSV importer does not import those values and the Date Updated field will be set to the latest date, and not to the value you specified in the CSV import.

This happens because Jira considers the CSV import on top of an existing issue as an update to the issue itself and thus, puts current datetime in the updated date field. 

The updated date field will reflect the value from the CSV if the issue is not present prior to the import.