Deleting data from iCloud should be hard from a stolen iPod (should require a password)

I was partially relieved when iCloud contained my photos after my iPod5 was stolen. This lasted 1 day. Now there are no photos on the iCloud. This erasing should be hard for the thief. (they do not know my id pswd) esp after Find my device had been activated. What a user-unfriendly service.