Thank you for the feedback. I've passed this on to our Product Strategy team.
Regarding "Complete" activities, we do remove all Export activities that have a status of "Complete" after 7 days. Import activities are kept on a longer basis in case you need to look at these for your records. Currently we do not have any way via the API to remove these, however they can be deleted from your account on long in. This is certainly a feature we could add in the future.
Dave Berard Senior Product Manager, Constant Contact