It's to make sure it's yours. It's not stupid. There are a lot of scammers who set up auctions like this with pictures without their username next to it, thinking they can score easy credits with a fake auction. But you won't be able to get the credits unless you ship the item. It'd be best to but your username there. It'll guarantee you in receiving more credits.
Item don't have a description, picture provided of disc just can't determine conditions of the item. Does this disc have any stain fog film, scratches at all?