clearing messages when you leave the chat window will make people not use it
With WhatsApp picking up speed in my close friend circle, Facebook messenger being used for everyone else, and the occasional Google hangouts messages when I feel like being online, I don't think even taking the "ephemeral" approach is going to make a difference in persuading me to start picking Snapchat over competing platforms. Snapchat is fun because as other users mentioned, I get to send bullshit one-off joke snaps to my friends. I don't want to maintain a conversation of any sort through another app. However, knowing the conversation is immediately cleared further dissuades me. The point of this feature is that it's good for non-committal "conversations" and very easy to engage/disengage. But I already have WhatsApp for that, and I have group conversations there, and my messages aren't deleted.