This is why we can't have nice things.
This is why Marketing shouldn't promise things that they can't deliver. They should know that "unlimited" has a specific meaning and if they don't mean it, they shouldn't promise it.
If they promised storing an unlimited number of photographs, it doesn't mean they need to promise that each photograph can be of unlimited size. The number of people who have 1 GB bona-fide photos is vanishingly small, and Amazon is of no obligation to serve them.
However, the next step from "abusers" would be, of course, to store huge files as many separate photos on Amazon.
But I'm not sure why "unlimited" is the point here. If they did limit it to 15 GB (like Google drive's free storage), the abusers could still save 15 GB of non-photo files on this service. This would be less of an abuse?