Why would I want to reset GoZyncMobile?
The reset makes GoZync mobile think that none of the local files have ever synced before. The main reason to do this is that if you download a new version of a mobile file set to "round trip", you may need to start the sync all over again to get your records down from the host. Without a reset, GoZync would only send you records changed since your last sync, which may not be what you want.
Reset does two things: it clears the "last sync time" and it wipes the table we use to track field level merge. This means you could have a longer than usual first sync after resetting if you're using Field Level Merge.
However, since you can "seed" the field level merge (FLM) database before you deploy, many developers will do this before distributing mobile files so their users don't need to reset. Thus "reset" becomes more of a developer feature than something end users need to do.