A common approach on Android. Nobody really seems to know exactly why, but evidently crap accumulates, either from old apps or from sloppy in-place OS upgrades. A full reset clears all the crap, and you start anew.
I prefer to skip even the backup step, instead relying on cloud sync for contacts etc, and manually dumping a couple apps.
I prefer to skip even the backup step, instead relying on cloud sync for contacts etc, and manually dumping a couple apps.