I don't totally see the point to these arguments. The inherent nature of the technology we have means that if they can view it once, they can view it as long and as many times as they want. Anything trying to restrict that is just futile -- look at DRM.

Snapchat has never given that particular illusion of privacy. As the most common and basic example, it has absolutely no way of stopping people from simply taking a screenshot of your image. Snapchat is meant to be used to share throwaway photos without the social expectation that comes from putting it on somewhere like Facebook. Anyone who uses the application learns quickly that someone can potentially store the photo they sent -- in a vast variety of ways.