When you give the player a rare but powerful item which can only be used once but is never really required to proceed, most players will not use it at all, because they are waiting for the perfect moment. But even when this moment comes, they will still be reluctant to use it, because there might be an even better moment later. So they keep hoarding it for a moment which will never come. 

In the end, they will carry the item around until it is outclassed by other, more readily available resources, or even until the very end of the game. That means that such one-shot items don't provide any gameplay-value at all. They are simply too awesome to use.

What can you do to encourage the player to make use of their one-shot items and not hoard them?


Question: Why would one shoot a fully blurred picture?
Answer: Shooting blurred photos can be considered opposite of black and white photography - while black and white is about hiding colors to bring out shapes and shadows, blurring helps to reveal colors by hiding shapes and shadows. An interesting subcategory is a combination of the opposites - black and white blurs - where distractions by both details and colors are hidden away to bring out larger shapes or patterns.

Blurred images could be used for several purposes, like


to hide boring shapes that have interesting colors;
to hide unwanted details on interesting shapes;
to give feeling of mind-boggling motion;
to evoke memories - colors/shapes alone can trigger some memories stronger than same image with details - because only the colors/shapes match memories of other people, not the details;
to initiate curiosity - a blurred image and a catchy title might induce a person into taking some action, like reading accompanying article;
to differ from the ubiquitous super-sharp photography;
to suggest a hurried "caught moment";
to suggest that someone is leaving (walked out of focus);
to create some new shapes with light sources leaving stripes in the frame.


As an example, Michael Orton is a photographer who has taken lots of great blurred images. The roots of creating blurry images are, however, much older, starting with (pre-)impressionist painters like Joseph Mallord William Turner (aka "the painter of light") and Claude Monet.