Why don't they just add the option to send a photo for a time limited time to Facebook chat? Then, game over, surely? I mean ffs why do you need a separate app for this, all it is is sending a photo that deletes itself, what is the fuss??
The problem is that nobody would be very interested in that, because nobody thinks Facebook won't keep the photo and stick it on your news feed someday.
Which... is exactly what will happen with this app too.