I would guess taking paypal (i.e. billmelater, etc) would make it much easier to complete the purchase for some people (read worldwide). Also I've visited the ducati.it store online and it has some items not found on ducatiusa so while I've never tried to order from .it, I wonder if the ebay store will contains ALL ducati items? That would be cool and probably easier for them to maintain rather than all those stores.
Finally, I find it simpler to buy stuff on ebay; hopefully they include all the nice pics. Makes them a bit more competitive against all the ducati stuff you find currently on ebay.