The drive needs a Full Format because it needs the entire file structures set-up, so the FAT actually has blocks and sectors to track, rather than a chaotic mess. This is why when you buy a brand-new unformatted hard drive, you cannot give it a Quick format. On the other hand, what a Quick format does is lay down a blank FAT and directory table without checking for bad sectors. In simple terms, a Full format will truly scrub through the hard drive from scratch, rebuild all of its file structures, and scans the drive to make sure that everything is on a satisfactory level.
