Banning the application could be justifiable (don't know the details), but removing everyones user photos just because they were uploaded with a certain tool, wow, that's messed up. I simply don't have words for it.
I don't think the posted content are actually deleted though, they should be unhidden when the app is unblocked.
I can see why people would be bitter... FB just deleted their photos because their upload method was "wrong".
If they said there was no possible way to examine the situation, or that they would restore your photos if you waded through an indemnification click-through, then OK, I can understand.
But just deleting the photos with no warning or even notification?