Is there any reason to use PSE catalog backup if I am using Windows 8 to automatically backup all files?
Catalog backup is file backup+tag/album backup. It ensures that all the tag and album associations you did in Organizer on my machine can be seamlessly transferred to Organizer on another machine.
Yes, all the organizing work (tags, albums etc) will not be available by Windows backup. Organizer's backup ensure that the state of PSE on machine will be exactly same on another machine after restoring the backup. For more details refer to: http://help.adobe.com/en_US/elementsorganizer/using/WS3d021fd412237a2f 14afb0171392eec10c6-7ffe.html